Marks on Porcelain Pavers

[Toppers]

We have a small porcelain paved area on our back garden which was sealed after being laid, the wife put some decorative plant pots on it which once removed have left circular brown marks on the pavers, I've tried to jet wash them off but they won't budge, any suggestions to clean it up and prevent it happening again.

[Dave Jones]

https://en.wikipedia.org/wiki/Sodium_hypochlorite