Cyano Chaos...

[Ruth]

Ditto on the fluval - I have never had success using canister filters for anything other than carbon. Unless you are absolutely obsessive with your maintenance and have a low bio load you are going to have algea problems in my experience. If you still can't get a handle on it you may want to consider either cooking (see various threads on RC for infomation on this) or just replacing it as it could be that you have a build up of crap in your rocks.