this might sound daft...

[big mick]

I do use a gravel cleaner but only every few weeks and I would like to point out an error on my part.....the ammonia level is 0.1 not 1.0 as I put, sorry.......I was wondering why everyone was saying it was too high but that was my fault.

.....I dont know if that makes any diffrerence to everybodies advice?

also thankyou all very much for your advice.