Green water

Jul 3, 2017
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United States
we have had green water ALL summer and can not see our fish also have found two of the comets dead and with no marks on them . put ''api algaefix'' in pond every 3 days 13 times and another nine times from new bottle with barely noticable results . also tried another water clarifier with zero results . pond is about 2500 gallons with filter and water fall and for past 10+ years has been mostly crystal clear . any thoughts appreciated , i think . . . peace....PS . it does seem to have deterred the heron .


Jul 12, 2009
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Mount Pocono, Pennsylvania
Hardiness Zone
This is a really common problem.
Don't get discouraged by the replies you get.
We are here to help.

Most likely what has happened is your pond has hit a tipping point. Most likely the fish have grown and multiplied and your filter cannot keep up with all the fish waste.

Nature has a fail safe to protect your fish and that is the free floating algae that makes the water green. Without that algae, your fish would likely start dying off.

You can increase your filtration and add tons of plants. Plants compete with algae, starving it out. (Algae is also a plant)

Stop with the chemicals. Algaecide has been known to kill fish, no matter what they tell you or you read on the bottle. We get threads about this all the time. People adding algaecide and all their fish died.

Improve you filtration and add plants.

It won't clear up overnight, but nothing you do to a pond ever does. It always takes time.

Now my bog filter plug:
I too had constant green water as you do. I knew I had too many fish. They just keep multiplying.
I added a bog upflow filter to my pond and within a week of starting it up, the water cleared.
If you are interested in an almost maintenance free filter, check out the many threads here about creating a bog. They can be huge and complicated or very small and simple, even made out of a plant window box or stock tank. It's all relative to the size of your pond. When completed, they just look like a planter full of plants. Again, plants are one of the important parts of the ecosystem.


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