Green Water

[duff]

I set up a 265 gallon tank this spring and am now in a heated battle with green water. The tank has 150 lbs. LR and 500 lbs. southdown with 50 lbs. ls. In my refugium there is some macro algea that does not seem to be growing. I had a cyano outbreak that I controlled by turning the lights out and got a large clean up crew. Presently the glass, sand and rock are clean. The levels in the tank are zero, and all fish are in a QT. The lights were out for over a week. I turned the lights on this morning and the water is turning greener by the minute. I have tried phosguard and phsphate absorbing sponges with no result. Any ideas?

 

[bang guy]

If this is a new tank then you can relax... it will just go away on its own. If this is an established reef then you have a Diatom bloom resulting from excess nutrients.
Before using products randomly, can you test you water and post the results?

 

[duff]

Thanks for responding. The only tests I have are for NO2, NO3 and ammonia-all are zero. The tank is new. What would happen if I left the lights on all the time and did not add anything to the tank? The goal being to rapidly deplete whatever mineral it is that is causing this outbreak and starve the algea. What test kits should I pick up?
Thanks

 

[bang guy]

phosphate is a primary nutrient so that would be a good test.
What is the source of your water?

 

[duff]

I'll head out and get a phosphate test. I have been using tap(I know I need RO/DI) in all my tanks and have not had an outbreak like this. Is it because of this tank is much larger? What type of RO/DI unit can I hook up to the faucet? I looked at the kent models from this site. If I start doing small water changes with RO/DI water how soon do you think my water will turn clear?

 

[bang guy]

I don't know. It will most likely clear faster with the Ro/DI though.
It doesn't surprise me at all that your Nitrate levels are low. The algae bloom is most likely sequestering all available Nitrate. Water changes will remove both, the algae and the nutrients.
Your algae consuming critters will slowly increase in population and they should be able to control the bloom.

 

[bullshark]

The same thing happened to me with a FOWLR tank. It was green for 2 months, no matter how many water changes I did. All of a sudden over the course on ONE day it went crystal clear. I did nothing. Weird.