Green Water - what do I test for first?

[woofwoofgrrl]

I have a lovely case of green water. I have a 30 G med lo-tech planted tank with LED lights. I have java fern and chain sword, both of which are growing well. My lights are on for about 12 hours a day. I just put them on a timer, and 12 hours is actually shorter a photo period than I before I added the timer. Right now the lights are off hoping to nip the green water in the bud. However, because my photo period is shorter now than it had been in the previous months, I'm suspecting it's a nutrient imbalance not a lighting issue. My nitrates are also reading 0 - I took two measurements after shaking the bottles really well, just to be sure. (Nitrates and Ammonia are also 0, FYI). My pH is 8.0, my hardness both Kh and Gh are right around 5.
What else should I measure? I was looking at the 'diagnose your algae' page linked to in many threads, and it lists a series of parameters and their ideal ranges. Which of those should I look at first and where can I find the test kits quickly?

Are my fish in any danger?

Thanks! Christine

 

[Philly33]

Do pwc frequently and reduce photo period to 8hrs to start. Someone else will chime in with more info.

 

[jetajockey]

It could be a nutrient imbalance but the lighting is really what spurs it on. I've never seen green water in a tank with a short photoperiod and/or low lighting. Is there any reason why you are running it for 12 hours?

 

[woofwoofgrrl]

Before I put it on the timer I would turn it on when I got up and then turn it off when I went to bed, so that was generally more then 12 hours. When I put it on the timer, I figured 12 would be a good approximation. Other than that I have no good reason for running the lights for 12 hours, other than I like to look at my fish.

The LED's have a lumen equivalent to 2 T5's with really good reflectors.

 

[Crepe]

Do you know a willow tree? Cut off a leafy branch or two and stick them in like you would flowers in a pot. Your green water will be gone in under a week.

 

[woofwoofgrrl]

I just so happen to have a willow in my back yard! I'll give it a try. So what about willow makes it clear up the algae?

 

[Crepe]

It saps up all the extra nutrients in the tank and on top of that has some phytochemicals that kill algae.

 

[woofwoofgrrl]

It will restore balance to the Force! Awesome! I just stuck two branches in there. The fishies were very curious!

 

[woofwoofgrrl]

20 days later....

Okay, so we're 20 days later and the green has mostly cleared up but there's just a touch of cloudiness left. Should I remove the willow and put some carbon in my filter for a day or two or is there something else I should do to fully restore clarity?