Ongoing algae problem
I need help. I've had aquariums for years with no major problems. But I can't figure this one out. I'm hoping someone can enlighten me.
I have a 65 gallon, tall, freshwater planted tank. It's been set up since May 2008. It's relatively heavily planted, with maybe a dozen fish. Fish and plants are healthy and thriving.
For two years the tank was beautiful and I did normal maintenance on it.
Than late late last spring (May?) the water in the tank turned milky/chalky, and then turned green. I figured it was algae and that I could get rid of it with some effort. Tested the water chemistry and everything was in normal ranges. I did appropriate water changes. Made sure that I wasn't overfeeding. Made sure there was no decaying plant matter. Did more water changes. Nothing helped.
In August (three months later) I replaced both compact flourescents (1 actinic 420nm 96w and 1 daylight 6700░ 96w), and continued with water changes, water tests, etc. The water stayed green.
In December (another four months later) I emptied the entire tank, replanted it, and it looked great for about three weeks. Then the water turned milky, then green, and my tank looks like the Emerald City again, and I'm finding that I'm no Oz.
I have an Eheim canister filter which pumps 250g/h.
Any ideas? I'm about to try replacing the actinic light with a second daylight bulb. Any thoughts? Recommendations?
Thanks for your help!