Green cloudy/hazy water

[A.J.]

I did a search and found this forum, thought maybe you could help?

I'm about to lose my mind with this cloudy/ hazy water. It's like there's a green tinted light diffuser in the glass or something.

I've tried everything. Nothing has made clear up. I even spent $100 on a UV sterilizer and after 4 days, there's been no change. Water changes, gravel vacuuming, cannister cleaning, 4 different types of algaecide. I even tried a 3 day black-out. Nothing has worked.

Here's a little history...

I bought an established 55 gal tank complete with 6-7 fish about 3 months ago. From the first day I bought the tank, I've had green water. The people I bought the tank from said they used an algaecide from time to time, and I didn't think a thing of it.

We filled a 5 gal bucket about 2/3 full of tank water, put the fish in the bucket, removed about 90% of the water from the tank, transported it home, put it on a stand, assembled the filter, filled it with water and it's been greenish/ hazy ever since.

When I first got it setup I read the directions on the algaecide wrong and gave the tank 3 X the amount I should have, I'm an idiot no question. Well, this killed every fish in the tank. I did 4 major water changes, like 40-50%, got rid of the algaecide and replaced the fish.

I now have 9 assorted cichlids and one pictus cat. The cichlids are mostly juvenile. There's one peacock that's about 3 inches long, the rest are 2 inches or smaller. The fish are all perfectly fine right now. The water levels are all spot on. Nothing is out of place. pH, nitrate, ammonia... all of it is at either safe or ideal according to the tests.

I have a Fluvall canister, I do weekly 20% water changes, and vacuum the gravel regularly. Inside the cannister I have 2 activated carbon filters on the bottom, a phosphate/nitrate/ nitrite filter in the middle under a water polishing pad, and the bio stuff on the top. I have a turbo twist UV sterilizer attached to the return line, and the water flow from the Fluval to the sterilizer is set at about 40% of capacity. I also have 2 air stones in the tank. And it's never in direct sunlight. The tank faces south. There is some indirect sunlight though. The light is never on more than 6 hours a day.

I've done a 3 day blackout, used 3 different types of algaecide, have done regularly water changes, nothing has cleared the problem. Right now, after massively cleaning the filter (with tank water not tap) the still tank has a greenish hazy tint. I also took the hoses off and cleaned all the nasty sludge out of them.

I would almost bet my house that in a couple days the tint will darken.

I'm thinking, as a last resort, of selling the tank and joining the circus. Or maybe, there's just a ton of minerals in my water? I use the water from tap to fill the tank. It's softened.

What if I added some plants?

Mommy, make it stop.

Seriously, any pro tips will be met with a great deal of gratitude!

[mom2reds]

Just a guess but you might try not using softened water and use RO or try to bypass the water softener and you plain tap water. If you can use a liquid test kit like API freshwater master test kit and try to give us the ammonia, nitrate, nitrite and the ph levels of your tank as well as the water temp. I would also sugget that you not use anymore of the algecides, the only chemical you should use is the dechorinator.

[mom2reds]

You may also try this web site gwapa.org

[A.J.]

Hi Tess, thanks for replying.

Here are the levels:

> 20 Nitrate

0 Nitrite

> 24 Hardness

> 0.5 Chlorine

40-80 Alkalinity

~6.8 pH

Temp: 78 degrees

I'm not sure the non softened water is a viable option. Maybe when summer hits, as right now the only water not softened is the hose water outisde.

I guess I could buy some RO water, but that's a little expensive isn't it? Would I have to do that every time?

What about adding plants? Would that work?

[mandown123]

Go to the fish store and see if they sell RO or RO/DI water. Its a cheap fix rather than buying your own RO unit. I looked into it but decided I should buy from LFS for now because of $$ issues.

At least if it continues you can be 100% sure it isnt your water that is the problem

[Purrbox]

Green water is generally caused by a small spike of Ammonia in the presense of water. Often the Ammonia is indetectible by the time that the Green Water shows up, since it usually corrects the situation that first causes it. I would recommend a large water change followed by a 3-5 day blackout (no tank lights, completely covered so no light gets in, no peeking) and finished with a large water change after the blackout is complete.

[An t-iasg]

You could add plants but I would try to get this green water issue fixed first. Plants and fertilization can be another issue entirely. Planted tanks can have green water problems too. I don't think plants would be a sure fix in this situation.

Make sure you're not overfeeding. Do you change the carbon regularly? If you don't change it, it just becomes a biological bacteria medium. I have read (and have read it disputed too) that old carbon leaches the contaminants that it removed back into the water. Since there's no way to be sure, if you're using carbon you should replace it every few weeks.

Edit -- had some more thoughts. It's strange that the UV sterilizer isn't helping. I'm really not sure how long one would take to work, but you should see a difference after 4 days. Check the manual and make sure the waterflow is at the correct rate for the sterilizer (water passing too fast through it probably won't help). If the sterilizer still doesn't seem to help, something must still be generating this algae. I wonder if it's the ammonia level. Have you detected any ammonia from your tests? Why do you have a phosphate/nitrate removing pad in your filter? I would try taking this pad out and then checking ammonia, nitrite, and nitrate readings. Even though you posted a 20 ppm nitrate reading, I wonder if the tank is cycled.

[A.J.]

Originally Posted by An t-iasg

You could add plants but I would try to get this green water issue fixed first. Plants and fertilization can be another issue entirely. Planted tanks can have green water problems too. I don't think plants would be a sure fix in this situation.

Make sure you're not overfeeding. Do you change the carbon regularly? If you don't change it, it just becomes a biological bacteria medium. I have read (and have read it disputed too) that old carbon leaches the contaminants that it removed back into the water. Since there's no way to be sure, if you're using carbon you should replace it every few weeks.

Edit -- had some more thoughts. It's strange that the UV sterilizer isn't helping. I'm really not sure how long one would take to work, but you should see a difference after 4 days. Check the manual and make sure the waterflow is at the correct rate for the sterilizer (water passing too fast through it probably won't help). If the sterilizer still doesn't seem to help, something must still be generating this algae. I wonder if it's the ammonia level. Have you detected any ammonia from your tests? Why do you have a phosphate/nitrate removing pad in your filter? I would try taking this pad out and then checking ammonia, nitrite, and nitrate readings. Even though you posted a 20 ppm nitrate reading, I wonder if the tank is cycled.

Hi An t-iasg

Do you change the carbon regularly?

I've "changed" or replaced the carbon one time since purchasing the tank. Most of the time, I'll rinse it out real good in tank water, which probably render's it useless.


Check the manual and make sure the waterflow is at the correct rate for the sterilizer (water passing too fast through it probably won't help).

Affirmative. I've checked and rechecked the manual. I've got the flow set at about 40% capacity. Well within the manual's recommendation.


Have you detected any ammonia from your tests?

None at all.


Why do you have a phosphate/nitrate removing pad in your filter?

Because I read that is what the algae eats. My thought was to cut off the food supply.


I wonder if the tank is cycled.

I've wondered this too. I bought it used, it's an established tank at least a year old. But still, if the UV sterilizer isn't working, I have no idea. Every source, documentation, review... all said that the UV sterilizer will make the green water go away in 24 hours.

I bought it Monday. Have had it running all week, and there is literally no change. And yes, the bulb is on. Yes, I've checked the connections.



Let's say the tank is cycling, what can I do? I've got a bunch of fish, are they in danger?


Here's what it looks like:

[An t-iasg]

The green water is not a danger to fish. I would remove the nitrate/phosphorus pads in the filter. They are obviously not helping and they may just be releasing the DOCs and various impurities back in the tank. Then you can get a true reading of your nitrites and nitrates. It's puzzling that you have no ammonia. Green water usually thrives on ammonia and excess light.

When I had a canister filter, I put a coarse pad on the bottom, a media bag with bio-rings/noodles in the middle, and a big piece of fiber floss on top. I didn't have compartments in my filter so I had to stack the media. Rinse the media only once a month-six weeks in the removed tank water. I changed the filter floss more often. You may want to make some dechlorinated water to do your rinsing in now. Rinse the media to get any trapped debris away that may be feeding the algae. Don't overfeed - that's where the excess phosphates can come in.

Try several large water changes on consecutive days. Try three 50% water changes and then two or three 25-30% water changes on 5 or 6 consecutive days. Don't vacuum the gravel, just do water changes and rinse the media. I would do a good media rinse first. Remember to check for ammonia/nitrite/nitrate also.

[Purrbox]

Is the water actually hazy or is the green dusting on the glass surface? From the pictures it almost looks like you've got green dust algae on the glass instead of Green Water in the aquarium. This would help explain why the UV filter hasn't made a difference. Green Dust Algae just needs to be left along for a few weeks and then can be brushed off during a water change and then it won't return.

If it is actually green water, then you definately don't have a very severe case at this time. A black out should probably wipe it out rather quickly.

As An t-iasg has recommended, get rid of the phosphate/nitrate pads.