Thanks for the replies,can't use a chiller cos I can neither afford to buy one or run one,can't see a fan helping because there's not much in the cabinet to point it at (just a filter canister and some big pipes).
I've switched off the Chinese 30w powerhead and have done a 30% water change to cool it down,I'll wait and see if that helps and let you know how it goes.
Canister creates heat, fan blows air around tank and cools it. Works for me but gl.
#1 S. Vettel