Green water?

Sep 27, 2009
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#1
I have a forty gallon tank with 18 platys and three Cory catfish. It has plenty of plants in it too. Lately my water has turned green. Why is it doing this? I've done algaefix for three days like it say to do And nothing has changed. What is another way to get rid of the all the green?
 

fishwish34

Medium Fish
Jun 27, 2010
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#2
I have this problem, too. I think that it is caused by too much light hitting the tank. I read somewhere that you can wrap towels around the tank and sort of black it out for a few days to kill of the algae, but I haven't tried this.
 

Aug 13, 2010
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Sicklerville, NJ
#4
Hold on....before you try anything, make sure it will do more good then harm. I do not use algeafix, but I am sure as with other meds, you need to remove the carbon from your filter if you have.

What is the photo period (how long the lights are on) in the tank? What type and how many plants? Do you have CO2 or add ferts? Can you post a pic of the tank? What is your water change schedule?
 

Sep 27, 2009
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#5
I do not add co2 or ferts. I changed my carbon today after I used the algaefix. I change my water every Tuesday about ten to fifteen percent. I have some moneywort, some long grass stuff, and two green Cabombas. My light are on for about twelve to thirteen hours. I will put a picture on.
 

Feb 27, 2009
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#8
Green water is normally caused by too much light (you do not have too much, although the photoperiod could be less) and/or too much dissolved organic solids.

I'd lessen the photo period as suggested, and do 50% water changes each week until it clears. Once its gone, I'd do regular 30-50% water changes weekly.

The picture doesn't show enough detail, do you know what the grass-like plant is on the right?
 

Feb 27, 2009
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#10
Mondo Grass maybe? Not true aquatic plant if it is....
I think so too. It doesn't look healthy at any rate, which is contributing to the extra dissolved organics as it decays.

I get so irritated at my LFS. I was there a few days ago to get some Prime and they have 5 plants for sale in their store, 4 of which are not aquatic. The only one that was aquatic was a horrid looking bunch of java ferns, holes in the leaves and completely covered with beard algae. Its no wonder people choose to buy the mondo grass, draceana, green hedge and bamboo, none of which can survive long-term submerged.

Looking at your photo again, it looks like the tank is situated between two windows. Even though there are blinds on the windows, they still will let in a lot of extra light. I'd also suggest either moving the tank so its not so close to windows, or putting a background on the back (and maybe sides) of the tank to block out light from entering.
 

Last edited:
Aug 13, 2010
870
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Sicklerville, NJ
#11
I am so lucky in that my LFS is OLD SCHOOL! he breads alot of fish himself, he never tries to sell you anything you don't need and is a wealth of knowledge!

So the OP should start with lowering the photo period, I suggested 6 hours a day. What do you think OC?
 

Feb 27, 2009
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#12
he breads alot of fish himself
I hope you mean BREEDS and not BREADS (unless he's eating the fish!).

So the OP should start with lowering the photo period, I suggested 6 hours a day. What do you think OC?
With just over 1WPG, I'd shorten the photo period to 10 hours, personally. You don't want to starve the plants you DO want to grow. Get a timer, make your life easier!

I'd also remove the plant on the right, if its mondo grass or not, as its not helping at all. Then I'd pull up the rest of the plants and let them float. The atmospheric CO2 they will have will give them a boost and help to consume the disolved organics too.

Keep up the water changes until it clears, then replant the plants that ARE aquatic, and it should be good to go.