Green Water!

[dablwa]

Hiya,
My Tropical Freshwater tank's water has turned green. I part change the water weekly but this only lightens it a bit!
Any advice would be very welcome.
David

 

[dablwa]

Hiya,
My Tropical Freshwater tank's water has turned green. I part change the water weekly but this only lightens it a bit!
Any advice would be very welcome.
David

I have now found a number of forums on this site dealing with this problem so hopefully will get it sorted.
David

 

[glolite]

Well done for doing your own research on the forums. We're a bit slow this time of year, people away on holidays etc.

Welcome to the forums

 

[rdd1952]

Hello and welcome to the forum.

Green water is quite common in new setups and is caused by a couple of things. Actually what makes the water green are diatoms which is free floating algae. These diatoms feed on silica which comes from both the substrate and from the silicone that seals glass tanks. Once that silica is gone, the green water should clear up UNLESS you have your tank in direct sunlight which is the other major cause of green water.

Obviously, if the tank is in direct sunlight at any part of the day, you really need to move it or you will always struggle with green water. As I mentioned, it should clear on it's own eventually but it will take a while.

Another option is a UV Sterilizer. They run off a powerhead or a external (canister) filter. The water passes through it and through a light which basically kills everything that passes through it. The algae are killed in the process. They are expensive but do work. The link below is to a thread I did a little over 4 years ago showing how it worked on my tank.

UV Sterilizers

 

[drobbyb]

Just to add with what rdd has said, the presence of ammonia, even an undetectible level, will trigger green water if some of the other factors are present, such as sunlight (or bright tank lighting).

Waterchanges will do very little to stop the outbreak. What I have done in the past to great effect is this: do a large waterchange, say 80% and wrap the tank with a large blanket, paper, or other medium to block out all light for a period of 3 days. It's vital that no light penetrates the barrier. After 3 days of no light perform another large waterchange and gravel vac to remove the now dead algae.

If there is sunlight hitting the tank, you may want to move the tank out of the sun to prevent this from happening again.

HTH

 

[alan3513]

Agree with drobbyb. Last Monday i did what he said following the advice from aaronnorth. It worked a treat and so far (5 days) since i uncovered the tank i still have a crystal clear tank water.

 

[OldMan47]

Welcome to the forum Dablwa. green water algae has 2 things going for it. First it is harmless to your fish so it is not a crisis in terms of caring for the fish. Second, as others have already said, it will clear on its own unless you have a very long period of light from your lighting system or get some direct sunlight. I have tried, in vain, to grow green water and have always failed within a week or two of placing my starter culture into a tank. The only time that I had any success was when I dosed an outdoor pond with nitrogen and added a starter sample of green water. That turned into a full green water bloom because it got direct sunlight and had enough nitrogen to feed the algae. After a few weeks, even that culture grew old and stopped growing and expanding.