Ongoing algae problem

[Daniel Powers]

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!

[thewife]

perhaps reduce your lighting and/or photoperiod, add flow, and regular water changes until it clears up. you haven't said what you've been doing for fertilizer + co2, but it may be possible that your plants aren't getting enough nutrients to outcompete the algae. that seems to be about the par-for-the-course solution around here

[DarkCobra]

That is a lot of light. Can you run only one bulb? Or raise the fixture so the tank receives less light? If you can't do either, try adding a few layers of window screen to block some of it out.

Then hit the algae hard with a three day blackout. Perform a 50% water change each day to remove dead or dying algae and the nutrients/toxins it might release.

Hopefully this will be enough to loosen the greenwater's hold on your tank for good.

[tlawrenson]

Might seem a little simple but a friend of mine actually did this. He bought a coconut shell from a pet store assuming it was for a fish tank (its for a terrerium) after a few days he had a major algea bloom, worst i've ever seen infact. Now i'm not saying you've done exactly this but have a good look for anything along those lines, did you add any driftwood? If so was it properly prepared? Just a thought.

[Daniel Powers]

Thanks for all of your posts. I appreciate you taking the time. I was sort of thinking that there wasn't enough light, that the plants (who are getting liquid fertilizer twice a week) weren't getting enough of the proper light, while the algae was thriving with measly light quality. I had reduced the amount of hours the lights were on, but it made no different. The idea of a three-day black out is about the only thing I haven't tried. I'll give it a go and see what happens.

[Kibblemania1414]

i also like the flow idea. nice!