Help! my tank is GREEN!

[sjsuper76]

I have a 120 gallon cichlid tank in my office with 2 48" natural daylight flourescents on a timer.

the timer was accidently set to run from 7AM-5AM (instead of 5PM). I noticed and fixed the problem because one of the bulbs burnt out and i checked the timer. So now I fixed the lights to run 7AM-5PM but only have one going now until I replace the bulb.

But literally over 4-5 days, the tank went from a few spots on the glass to GREEN water! Like Incredible Hulk green. =( How can I fix this? just lots of water changes? or can I dose the tank with Flourish Excel? There are no real plants in this tank because of the chichlids...

please advise, thank you!

 

[fort384]

Interesting that a reduction in light caused a green algae bloom. Water changes will help.

How old is the tank?

What are your water parameters (ammonia, nitrite, nitrate)?

What is your maintenance schedule for the tank? (how many water changes, how often, how much each time).

Excel isn't going to fix it.

 

[tyspot1000]

Doing water changes does not help with an a green algae bloom, but only feeds it In my past Experiences. I had to go with a black out or UV sterilizer.

 

[daileene]

+1 with fort.....

 

[fort384]

Ty, how would a PWC feed it? If you do a 50% PWC, you are removing 50% of the waterborne algae, and removing 50% of any excess nutrients in the water. The only way I could see it not helping is if there is ammonia or PO4 in the tap water.

Agree that a black out may be necessary. UV will help too, but probably not a requirement... the key is finding the excess nutrient (usually with a green algae bloom, that is light, but it doesn't look like the case here). Either way though, a blackout will eventually kill any photosynthetic life in the tank (even if that is not what caused this), and would be a good option here considering there are no live plants.

 

[tyspot1000]

Ty, how would a PWC feed it? If you do a 50% PWC, you are removing 50% of the waterborne algae, and removing 50% of any excess nutrients in the water. The only way I could see it not helping is if there is ammonia or PO4 in the tap water.

Agree that a black out may be necessary. UV will help too, but probably not a requirement... the key is finding the excess nutrient (usually with a green algae bloom, that is light, but it doesn't look like the case here). Either way though, a blackout will eventually kill any photosynthetic life in the tank (even if that is not what caused this), and would be a good option here considering there are no live plants.

Some tap water is high in nutrients which Green algae can feed off of. <- Im not sure if this applies to the OP, but I will tell him.

Original Poster: Before you start to do water changes to get the green algae bloom down, test your water source. If it is high in phosphates, you should consider using phosphate removers or find another water source. It's wise to also test for nitrates, as some water sources have elevated nitrates. It doesn't do much good to change the water if you are adding nutrients!

 

[fort384]

Agreed Ty!

 

[sjsuper76]

I meant to say that I think the algae bloom was caused by mistakenly setting the light timers to ON for 22 hours a day. (on at 7am - 5am) I fixed this mistake after the tank turned green. So now it is set for 7am-5pm. But the water is still green.

One of the 48" bulbs burnt out (probably from being on 22 hrs a day) so we only have one 48" bulb on there now...but the water is still green.

this tank is in the the patient waiting room of my clinic, so I want it to look as good, do you think turning off the lights completely from Friday 4pm until Monday 7am would be a long enough dark period to kill off the algae?

Should I not do any more water changes? I was going to do a 50% on Saturday to aid the problem.

 

[fort384]

I would recommend a pwc if this is a new problem that appears to be caused by the inadvertent long photo period and there is no reason to believe you have excess po4 or nitrate in your tap water. Try leaving the lights off too. That will only help. If that doesn't help get it under control you may have to do a blackout using black plastic. Even some light from the room or a window could keep the bloom going.

 

[Crepe]

I suggest a three day black out and water changes like fort and ty suggest -if your water quality from the tap is good. Erythromycin dosed at regular dosage (some suggest less, like half dose) or putting in willow branches in the tank will also kill green water.

In aquaria it's marketed as marycyn.

 

[BillD]

The good news is that the green water is not harmful, and may in fact be beneficial. I wish i had some right now. Regardless, water changes should help. Erthromyacin is used to kill cynobacteria, also known as blue green algae or slime algae. I don't believe it will have any effect on green water.