Jeremy Harris

The biggest problem with the domestic construction industry as a whole is that they rarely seem to have much in the way of any formal contractual procedure. Sure, a contract exists, simply because an offer has been made, accepted and a consideration has been exchanged, but it's rare to get a proper written contract, with clear and unambiguous terms and conditions, I think. This lack of any formal specification, terms and conditions, etc, works in the favour of contractors looking to quote the lowest price. They leave out the expensive stuff, like disposal of waste, so their quote looks good value. I know that we've paid out well in excess of £10k for waste disposal during our build, probably closer to £12k. Just getting rid of the spoil from the ground works was well over £9k, then we had at least three skips at around £260 a time, plus another two or three grab lorry loads taken away later at several hundred pounds a load, including land fill tax. The majority of domestic building work seems to be undertaken on the basis of a pretty slap-dash informal quotation and acceptance form of contract, more often than not lacking in pretty much all the key critical detail. I guess this is just the way that the domestic construction sector has evolved, but I know that we've spent thousands with contractors with little more than a very rough and ready outline of the specification of the work, and almost always without enough detail to be able to determine whether any specific item was or was not included in the original quotation. After a while you get to know how some operate; for example the chap we always use to do any landscaping related work has a personal policy of removing all rubbish and waste from the site when he's finished. It's memorable, because he's the ONLY contractor we've ever had on site that has such a policy! It's not written down anywhere, and nine times out of ten specs and quotations from him are verbal, or just a sketch plan and some notes, but we've worked with him enough times to know that we'll get a very good job and he'll leave things very neat and tidy when he's finished.

I think the reason that some of us (well, certainly me) tend to relate cautionary tales that point out that, as a self-builder, you really need to watch everyone and everything all the time, is because we've been caught out ourselves, and are kicking ourselves about it. I really hate to see other people get caught out the same way, and my hope is that by relating cautionary tales the word will get out and more people will be aware of the things they need to watch out for. I doubt anyone here hasn't had a screw up that could have been prevented if they were better informed and had taken the time to learn a bit more about the way things are done. Take my borehole saga as a classic example - I failed miserably in so many areas when overseeing that work that it cost me a load of money and perhaps a year of delay in total. With the benefit of hindsight none of those failings should have happened, I should have been sufficiently on the ball to spot them and stop them happening, but I wasn't. I only acquired the knowledge I needed to oversee a borehole being drilled and cleaned AFTER the work was done and the problem needed fixing. @Triassics comment about being wary of anyone that doesn't come recommended is spot on. On our build the only problems were with contractors/suppliers that didn't come by some form of personal recommendation. I'm not sure how we better improve the way we communicate here - it's made harder because purely written communication in an informal style, like posts here, are always going to be open to interpretation as to the posters true meaning. As @recoveringacademic noted, some of us post here when we are angry, depressed, overjoyed, even "under the weather", so that is bound to colour our phraseology, much as we might wish it didn't.

No external filters on ours, either, although there will be one on the intake once we've got the old house sale out of the way and I have some "tinker time" available again. The plan is to relocate the external intake a bit lower down, so it's more readily accessible, and fit a fairly coarse, washable foam filter, so it's easy to change/clean. I'm hoping that will extend the life of the fairly expensive pollen filter on the intake side of the MVHR unit itself.

I think most of us have been in that place more than once. For those of us that have spent years getting to grips with DIY or self-build I think we sometimes might forget that we were probably all pretty lacking in knowledge and skills once, screwed a lot of things up and got extremely angry at times. My wife still regales me of the time when I decided to install a central heating system in a fairly new house we'd bought in Scotland in 1993. I decided it would be neater if I ran all the pipes in the 2ft high crawl space under the ground floor, accessed via two hatches in the floor above, as it was in two sections. I'd assumed it would be easy, but the combination of my lack of plumbing skills, having to work flat on my back and shuffle around, whilst trying to run pipes, make connections etc, all the time being showered with fibreglass underfloor insulation, which was just suspended under the floor by netting, did cause more than the odd flurry of expletives. She didn't know that I either swore or got very angry until then...

Very true! The majority of people I asked to quote just failed to respond at all. This included window suppliers, frame suppliers, passive foundation suppliers, as well as quite a lot of trades people. I reckon that if you get a response from more than half the people you contact you're doing well. I did have one frame company get in touch with me about 3 or 4 months after I'd asked them for a quote, sent them drawings etc. They seemed surprised when I told them we'd selected a contractor two months earlier.

I don't think this is that new a problem. When I started asking for quotes I reckon around 2/3rds of the companies I approached just didn't respond at all. Same happened when I asked for quotes for passive slab foundations. Most of the bigger companies I asked to quote for things needed chasing, and I got the impression that it wasn't that they were over-loaded with work, but really because they couldn't be arsed to quote for a one-off house.

TBH, joking aside, that's a damned handy bit of kit. We must have had around 20 or so pallets that collected around the site, some decent ones, some rubbish ones. In the end our landscaping chap asked me what I was going to do with them all and when I said I hadn't a clue, he offered to take them back to his yard in his small tipper truck and then burn them. As it happens, about a month later he was building some raised beds for us out of stone and we were chatting about the amount of topsoil we needed to get in to do the lawn and fill the raised beds he was making. I'd remembered reading somewhere about putting wood ash in the bottom of raised beds, so he offered to fill his truck up with ash from his yard bonfire (some of which was from our pallets) and bring it over to use as a base layer, under the top soil in the raised beds. Not sure if it does any good or not, but at least it semi-recycled the old pallets, albeit with the release of a fair bit of CO2. If I'd had something that made it easy to strip the pallets I'm sure I'd have found a use for the timber somewhere. Anyway, stacked timber takes up a lot less space than stacked pallets. Next we need an easy de-nailer, to get the bloody awful ring shank nails out of old timber...

You've missed both the critical points I was trying to make. Yes, it's your life, and yours to choose how to live it and what risks to make, I think it's only reasonable to point out things that are dangerous and which it's clear you have no knowledge of - I'm really not doing this just to poke my nose in or be a nuisance, these are bloody serious issues.. Fact: Flexible cable insulation chemically degrades in contact with some forms of insulation, other plastics etc, whether or not the cable is in use. This has caused cable insulation to break down and fail in the past and there are warnings all over the place about it if you choose to check. It doesn't matter at all whether the cable is connected or not - it's a known chemical issue arising from the reaction of the plasticiser in the flexible cable insulation - the stuff that keeps flexible PVC flexible. Fact: Flexible extension leads are rated for use fully unreeled and in open air. Every one sold has a warning on it to this effect, for a very good reason. When surrounded by insulation that section of flexible cable is likely to overheat and exacerbate the breakdown of the cable insulation - unseen by you; you won't have a clue it's happening until one day when you plug that lead in and turn it on to use it and it silently starts to smoulder behind your wall. You may well have stopped using the lead before any fire breaks out - it could sit there smouldering behind that wall for hours and you would no nothing about it. If you're lucky the fire will self-extinguish, still without you knowing anything about it, because it's behind the wall, and sit there waiting until the next time you plug the lead in, before heating up again. If you're unlucky then you will die in your sleep when the fire takes hold hours later and the fumes from the insulation etc cause toxic smoke to fill the house. By all means choose to ignore the above - that's your prerogative, all I'm doing is stating the risks, because it's clear from your reply above that you are unaware of the chemical reactions that are known to happen between flexible cables and insulation and you seem unaware of the overheating risk caused by surrounding a cable that's only ever intended to be used in the open air (that's in the regs as clear as day as well, if you wish to check).

Even disconnected there may well be (probably will be) chemical reactions between the plasticisers in the flexible cable insulation and the insulation. It's a well-known problem. This means that the cable may be sat their degrading internally inside the wall without you being aware, as it's behind the plasterboard. In addition, flexible extension cables are always rated for use fully unreeled in the open air, so any heat from normal I²R losses within the cable can dissipate safely via the outer surface of the cable. When buried in insulation that normal heat cannot dissipate, so may well build up when the cable is in use, further degrading the insulation of hidden section of cable in the wall and adding to the unseen potential problem. The danger is that you won't be able to see any of this; it will be going on inside the wall, and may take months for the insulation to gradually degrade. It will tend to degrade from over-heating in use internally first, and from plasticiser degradation externally, I would think. The first you may know about the cable failing is it catching fire inside the wall, and maybe smouldering slowly, unseen, for hours before it breaks out into flames, some time after the cable has been used. I promise you that the very last thing I'm trying to do is be unhelpful. I have a fairly high tolerance for risk and would not take the time to post these warnings if it wasn't something that would keep me awake at night (it is).

I was surprised how big a difference bonding down 12mm thick bamboo with Sikabond 95 adhesive made. I think the key is that the relatively thick layer of very rubbery Sikabond 95 inadvertently acts as a pretty good sound absorber. Our first floor make up (except for the bathrooms) is (top to bottom): 12mm strand woven T&G bamboo, bonded with Sikabond 95, to 18mm T&G OSB3, laid on to 253mm high Posijoists, at 400mm centres 150mm acoustic rock wool (a really unpleasant job...) 12mm plasterboard ~3mm plaster skim The bathroom floors are: 12mm Travertine stone, laid with Mapei flexible adhesive to 9mm marine ply, glued and screwed to 18mm OSB T&G flooring, laid on to 253mm high posijoists, at 400mm centres 150mm acoustic rockwool 12mm plasterboard 3mm plaster skim Overall we haven't noticed any significant noise transmission at all. We do have rugs over the bamboo flooring upstairs, and tend not to walk around the house in hard soled shoes, plus we don;t have young kids bouncing around. However, we have had visitors to the house who wanted to see how good the sound resistance was, so one went and jumped around upstairs whilst the other listened downstairs and the sound transmission wasn't really noticeable to me.

Thanks for confirming that, @PeterStarck, I remembered you'd had serious slab problems and thought they were structural, rather than essentially cosmetic. I think it's easy to forget that laying a flat, smooth, structurally sound, reinforced concrete slab isn't that easy a job; even the very best contractors can get it wrong, especially when a few random factors like delayed concrete deliveries, kit breaking down, or the variable British weather, are thrown in.

This was a somewhat different situation to the one that I think@PeterStarckhad, in that the slab was structurally sound. I believe his had structural defects, rather than cosmetic defects. @lizzie, I've been told, directly, that you personally agreed to accept the rectification work that was offered, or did through your project manager. I know that your project manager failed badly in not doing his job, but did you, or did you not, accept the rectification offer that was made? If the answer is "yes", then I think it's unfair to continue to raise this at every opportunity, as you tend to do. By accepting the rectification offer you ended the matter, as far as any contractual dispute may have been concerned. On the other hand, if you still have not accepted any rectification offer, then I'd seek resolution with those responsible, and only if the responsible parties refused to offer to rectify faults would I go on any open forum and continue to regularly raise the matter again as if it were an outstanding complaint, which you are still waiting to be resolved. I will admit to having been told that you were content with the resolution reached over a year ago now. Was I lied to? I still get the very strong impression that your project manager let you down to a much greater extent than any other company you had working on your build, and that much of your, quite understandable ire, should really be directed at him.

I can tell you for sure that your floor was sub-contracted out to a company that had little of no experience of this type of foundation - your project manager knew this for sure, I know. That's not to say that the sub-contracted company shouldn't have done a very much better job, they clearly should have, and that's why MBC offered rectification work at no cost to yourself. Lessons were learned and the sub-contractor involved got additional instruction, plus, I believe, direct oversight on future jobs, to make sure there wasn't a repeat performance. Sub-contracting is normal, but in this case the sub-contractor didn't work to the specification they were given, something that was outwith the control of yourself, MBC or your project manager. All MBC could do was come up with a way to rectify the poor workmanship as best anyone was able, which I believe they did, at no additional cost to you.

1. Are the company's claims proven? Absolutely and unequivocally not. I can find no hard, independent, peer-reviewed evidence at all to support their claims. 2. Should we allow companies to be members of our forum? Yes, as long as they don't openly promote their products or seek to gather data from forum members to assist in marketing their products. Any company entering into a discussion on an open public forum knows before they start that open debate is a double edged sword, that can cause them reputational harm as well as reputational enhancement. An old acquaintance of mine, who was a kit aircraft supplier (I was once involved in kit aircraft design and manufacture) refused to join any aviation forum using his real name, or reveal any association with his company, solely because he felt that any customers who had experienced problems would raise them with him publicly, rather than privately, when seeking resolution. He felt, rightly or wrongly, that contented customers would, in the main, keep quiet, and as a consequence only the occasional problem would get a public airing. I'm inclined to think he was right, on balance. People are often quick to seek out forums and social media in order to complain, but far less motivated to do so in order to just say they had good, or acceptable, service, so the overall impression given can easily be very biased.

@lizzie, I can't help but think that you weren't well served by your PM. For £50k I would have expected you to have had far fewer problems than you did, and with the single exception of the cock up by the concrete floor sub-contractor (first time they'd ever done such a job, apparently) it does seem that the majority of your problems come down to failings by your PM in one form or another. Maybe the Internorm installers were also to blame for some of your woes - they are a reputable company that do seem to be let down by their sub-contracted or franchised supplier/installer network, from what I can gather.

Definitely a great deal safer than a cable that's buried in insulation and may well be gradually degrading, unseen, even when not being used or plugged in. Who knows whether any fault would trip whatever safety devices may be protecting that circuit. The wiring pre-dates the use of RCDs (it's red and black, which gives it's age away) and so that means it's likely that there is no earth fault protection on that cable when plugged in at all. I'll admit to doing a few dodgy things and taking risks from time to time (like I will often work on live kit, just because I'm used to it) so I'm not averse to living life on the slightly dangerous side, but even I'd not contemplate a PVC insulated flex buried in insulation like that. Just shoving an extension lead out of a window when you need it has to be a great deal safer. Apart from anything else, you're far more likely to spot any weaknesses or impending faults in the cable if you can see all of it.

It normally includes all costs that were needed for the actual build of the working house, including utility connections, runs for foul drains, rainwater drains, power and phone cable runs and gas pipe runs. It's not normal to include plot costs, or landscaping costs as a rule. For example, we bought our plot relatively cheaply (around £50k under market price) but then spent a bit over £50k getting it level and suitable to use as a building plot, and those plot levelling costs weren't included in our cost per m² to build the house, as I considered them to just bring the plot up to its market value. I did include the cost of drilling our water borehole and installing the treatment system in our build cost per m², as that was equivalent to a utility cost, in my view.

I'm really confused as to how the heck any form of CaCO3 is actually in the mains water. Ignoring all the other elements/compounds for a moment, hard water that only has hardness resulting from calcium, will have the following formula: H2O + Ca2+ + 2HCO3- There is no CaCO3 in the incoming water, so there cannot be any, in any polymorph, in the water leaving your device unless your device somehow causes CaCO3 to be formed and precipitate out. It matters not how this formation and precipitation happens, but the fact is that the solubility of CaCO3 in water is such that it would just dissolve again soon after leaving the unit, and the water would once more turn back to H2O + Ca2+ + 2HCO3- I cannot find any evidence anywhere as to how this process of forming CaCO3 under conditions that are not normally those that would initiate its formation and precipitation from H2O + Ca2+ + 2HCO3- actually happens. What's even more puzzling is how the CaCO3 that is precipitated out of solution in the form of aragonite, isn't then subsequently dissolved again. Of course it's plain nonsense to suggest that calcite enters the device with the incoming water, it cannot, as mains water that is below super-saturation point doesn't contain any calcite at all.

FWIW, MBC had virtually nothing at all to do with my windows and doors at all. They made the frame to my design, in terms of overall dimensions, door and window openings, etc. Their only intervention was after I'd complained (in passing) that the window company were a bit of a shambles to deal with. Unknown to me their MD took the trouble to drive down to Cork and give the window company an earful on my behalf; something that they didn't need to do and weren't in any way contracted to do - windows, doors and all the relevant opening sizes and specifications were 100% my responsibility, right from the very start. In fact, it's written into the MBC contract that all that stuff is my responsibility, as was loads of other stuff like me providing the scaffolding as required and on time, me providing skips as required, toilet, hand washing and first aid facilities etc, etc. The contract is a dozen pages long and is crystal clear as to what was my responsibility and what was theirs, which is one reason why I can't understand why some seem to think that project management was in any way a frame companies responsibility - it's clear in my contract that it's my job to sort that aspect out.

What happened with our build is this: As the designer, I stipulated the frame opening dimensions, to the mm. The frame construction company (MBC) made the frame EXACTLY to those opening dimensions. The window supplier was given a sat of exact frame opening dimensions. They insisted on sending their local chap around as soon as the frame was erected to check that the dimensions that they had quoted against were correct (they were). The window supplier then sent me a final contract, which included a dimensioned drawing of every single window and door, each with a unique reference number and its location. By each window/door drawing there was a box for me to sign to confirm that the dimension, opening directions, spec etc was correct (I literally had to sign and date each and every individual window/door drawing (around 14 of them, IIRC). The window supplier made all the doors and windows 5mm smaller all around *** as a fitting tolerance, to allow them to be slid in relatively easily and wedged up to get them all dead square. They fitted all the windows and doors in less than a day *** and were generally OK. I didn't opt to use their gap filling service but chose to do that myself, primarily because I wanted to be absolutely sure it was as good a job as was possible, and frankly I'm glad I did, as the company in general didn't impress me (although the doors and windows have been fine). The frame supplier wasn't supposed to be involved with the window supplier at all, but when I was having hassle with the window company MBC did go out of their way to help (Joe drove down to Cork and gave the window company bloke a bollocking and told him to engage with his customers more positively, from what I can gather). *** The gotcha was that we had one one window that was 2000mm wide, all the others were smaller. They turned up with two windows 2000mm wide and minus one window that was 1600mm wide. Luckily the reams of drawings that were in the contract, each individually signed, made it clear that they had screwed up, so they took the 2000mm wide window back and returned a couple of weeks late with the correct 1600mm wide one. This incident made me glad I'd had to sign off every individual window and door as a part of the contract.

Hiding a key is probably as good as a key safe, as long as it's in a very unlikely place to find by accident (i.e. not under a mat, flower pot, rock etc near the door). Many years ago I had a magnetic key safe that held a spare car key. It was just a small box with a sliding lid and a strong magnet that could be stuck somewhere under the car, in case you locked yourself out of the car with the keys inside (something that's pretty much been overtaken by technology, now, but happened to me more than once with a car I had that had a self-locking tailgate - no latch, had to be opened with the key). I've been toying with the idea of removing my old key safe (despite the promises that it was corrosion resistant it wasn't) and instead having a hidden key location instead. In practical terms I'm sure it would be every bit as secure as a key safe, perhaps more so, as there would be nothing to advertise that there was a key outside the house.

Dissolved calcium doesn't exist in hard water as ready-formed carbonate of any form, but as calcium ions, Ca2+ . Hence the reason that an ion exchange column can swap out calcium ions (Ca2+) for sodium ions (Na+) that the ion exchange medium has already been pre-charged with, leaving the water pretty much calcium free. So, although we know that calcium (and magnesium) rich waters obtained their calcium from dissolving calcium and magnesium carbonates, they don't contain carbonates in solution as such, but rather as calcium and magnesium ions. This is the fundamental problem I have with your statement that: This is flawed basic chemistry. CaCO3 doesn't exist, as such, in the water, as it has been dissolved, it is not in suspension, or held as some form of colloid. Dissolved literally means that the CaCO3 has been broken down to it's constituent elements within the water, in this case Ca2+ cations. The actual solution reaction is this one, and it relies on rainwater that is the start of our drinking water cycle containing dissolved CO2 (which it does, CO2 is, as we all know from fizzy drinks, readily soluble in water): CaCO3 + H2O + CO2 ↔ Ca2+ + 2HCO3- As is transparently clear from the above reversible reaction, the calcium in solution (the right hand side of this equation) is not in the form of CaCO3, in any of its polymorphs, it only exists as Ca2+ cations in solution. You can reverse this reaction readily to get CaCO3 out of solution, this is what happens when the precipitation criteria are met, but this reversal does not take place in normal cold water pipework, so the water flowing into your device does not contain CaCO3, either as calcite or aragonite, it cannot, unless something ahead of the device has caused the above chemical reaction to reverse, not something that normally happens in domestic cold water supplies***. This is the logic behind the point I made earlier that this "catalytic" unit allegedly uses kinetic energy from water flow to cause CaCO3 to form as a precipitate in water that is not super-saturated with Ca2+ cations (it does not exist as precipitate in the incoming hard water whilst it's in solution in the closed pipe system). I'll ask the same question asked above, as it wasn't answered. We are agreed that CaCO3 is readily soluble in water. We know that, when dissolved it is in the form of Ca2+ cations. We also agree that of two of the forms of solid (precipitate) CaCO3, calcite and aragonite, aragonite is significantly more soluble in water than calcite. What process stops the aragonite from being dissolved by the water immediately after the unit and the calcium returning to Ca2+ in solution? How can aragonite exist without being in solution in water that is not saturated? If, for some reason, the incoming cold water supply was super saturated with Ca2+ cations, such that CaCO3 was already precipitating out as calcite, then I can understand how that polymorph could be changed to another, aragonite. It's a process that happens naturally in some dry caves, producing rather nice crystals on dry surfaces, often referred to as aragonite flowers. However, drinking water, even in the hardest water areas in the UK, is massively below the saturation limit. *** There are conditions where CaCO3 can be forced to precipitate out from water that it not super-saturated with Ca2+ cations and which does not become super-saturated as a consequence of drying out. Local high temperature surfaces can cause it to occur (hence the scale build up on heating elements) for example.

I fitted our key safe during the build, primarily to give contractors a way to get in if they arrived on site before I did. Every time a team of contractors left, I changed the combination. I sited the key safe well away from the doors and house, in a location that would be hard to accidentally come across (it's pretty well hidden). Fixing the thing down in a super strong way doesn't matter, as no one is likely to go to the hassle of crowbarring it off a wall just to take it away and grind it open, IMHO. Our insurer had no problem with it (I did have to declare it once), and it is very handy to be able to give someone you trust a combination to be able to get into your house. They aren't cheap, though, if you want one with reasonable security. The first one I bought was deeply flawed, for example, in that it didn't matter what order you entered the combination, it still opened, plus it didn't allow repeat numbers in any combination. For example, if the combination was set to 1234, then it would open on 4321, 2314, 4231, etc. One of the contractors found this out so I swapped it for a (lot) more expensive one. Finally, I'd suggest not putting a key safe where any thief would be likely to look for a spare key (like in a meter cabinet, for example). Ours is easy to get at, but no one would be able to find it quickly without being given directions as to where it is, and for most purposes I think that's probably a good idea..

As this discussion is getting a bit technical, I thought it might help to state a few facts with regard to how calcium (and magnesium, although that's not the subject of this particular discussion) gets into drinking water in the first place. In the UK, almost all of it comes from rainwater that flows through limestone or chalk (both forms of calcium carbonate, CaCO3). As the water percolates through these rocks, it dissolves CaCO3 and the water then contains calcium (and magnesium) in solution. There is therefore abundant evidence that what we call hard water; water that contains calcium (and magnesium) in solution, obtained that calcium by dissolving CaCO3 from the rock layers it passed through. Another basic principle is that any solution that becomes saturated with a dissolved compound, will readily start to precipitate out that compound under the right conditions. A good example would be a glass shower screen in a hard water area. The water droplets left on it start to dry out, and as they do the concentration of Ca2+ cations starts to increase and carbonates start to form in each droplet, to the point where there is not sufficient water available to maintain the carbonates in solution. The result it at around the edge of each droplet solid carbonates start to form (both calcium and magnesium carbonates, but usually mainly calcium carbonate, CaCO3). Once the whole water droplet has dried out all that is left behind is the total dissolved solids within it, usually a mix of several compounds, but predominately CaCO3 in hard water areas. The same effect can be seen anywhere that the concentration of dissolved compounds in the water gets highly concentrated, so areas around shower, sink and basin drains, the ends of taps (where droplets evaporate away) are all places where CaCO3 will precipitate out. Run enough water over any such area of precipitated CaCO3 and it will dissolve back into solution, as long as the water isn't already saturated. Leave water sitting, or flowing, over CaCO3, dissolves it; it's the way the majority of caves in the UK have been formed. Most limestone caves start out as solution caves, where static, or very slowly moving, water just dissolves away the CaCO3 (limestone), forming solution chambers. Eventually these solution chambers may join up, through natural fissures in the limestone, and then water may start to flow more quickly. The rate at which CaCO3 is dissolved depends to some extent on the rate of flow of fresh water over it, so once passages have opened up to form underground streams the rate at which the CaCO3 starts to dissolve increases pretty rapidly (in geological terms) and these caves get larger and larger. They will carry on getting bigger for as long as fresh water flows through them, sometimes getting so large that they become structurally unsound and collapse. These collapses may be seen on the surface as sinkholes, and in limestones areas their formation increases the rate at which the CaCO3 dissolves, as the depressions they cause tend to cause surface streams to divert and run down into the underground cave network, so providing more fresh water to dissolve more CaCO3. The main point about the above stuff about dissolving CaCO3 is to illustrate that it's the way that we get hard water. It's not a coincidence that hard water is associated with limestone or chalk geology, and areas where other forms of geology predominate (Cornwall and areas of Scotland, to give but two examples) have naturally soft water. The reason is simply because their drinking water is not drawn from aquifers where the source water has flowed through, and dissolved, CaCO3 and so become "hard". I hope the above helps explain where I'm coming from in terms of asking for an explanation as to why CaCO3 that has somehow been made to come out of solution prematurely, in the form of aragonite, is able to remain as a fine precipitate despite the indisputable fact that the water carrying it is a pretty good solvent for CaCO3 and would fairly readily just dissolve it again and take it back into solution, exactly as it was before the sort of "catalytic" water treatment device described in the latter part of this thread. I may well have forgotten most of the stuff I learned when I did my first degree in physical chemistry, but the basics regarding solubility are really at best O level chemistry; there's nothing even vaguely complex here, with the possible exception of the way that calcium and magnesium themselves remain in solution once the original carbonates in the rock that contained them have been dissolved.

Good point, and one I hoped that you would pick up (I'd already made it in an earlier post, in reply to @jack and was, I admit, waiting to see if you would pick up on it, as it makes my point even more powerfully). We know that aragonite dissolves more readily in water than calcite, as aragonite is metastable, and thermodynamically it wants to revert to a lower energy state form of CaCO3, so what stops the aragonite that has been forced to artificially form, from the action of water flow supplied kinetic energy and the catalyst in your device, from dissolving straight back into the water in the pipework after the device and so becoming disassociated calcium ions, or perhaps dissolved bicarbonate, ready to precipitate out again as CaCO3 when the conditions are right?