Shrimpy said:Thanks for the replies.
Yes i am using normal gravel but i added fulvic grain to buffer the water and keep my ph down. Anyway, i found the problem! Dincho you were right, somehow my kh has crept up to 6!! My test kit is a little old so i bought a new api master test kit yesterday. The fulvic grain only has a 6 month lifespan so i guess thats what it was, i added some more yesterday so i will check again later.
Thanks again for all the advice
Lucky guess 😉