How do clean my pond water

[Tony Gutteridge]

I have a 500 gallon pond that is about 10 years old. I have one mirror carp (bought in error!) about 15 inches long plus about 30 assorted gold fish. Water is horrible green colour with what appears to be very fine debris within. During the afternoon fine dirty film forms on surface. I have two mechanical filters each with a uv filter. To try to clear the water I have added “Greenaway”. To remove sludge I have tried “Sludge Buster” powder. I recently have place a “Pond Bomb” in one of the filters. The water smells terrible. Nothing seems to have any effect at all

What am I doing wrong and what can I do to improve matters?

 

[WaterGardener]

What you are doing wrong is adding too many things to the water. Your pond sounds like it is overstocked and your filtration can't keep up with the fish load. You can increase the filtration and improve the type you have. You can vacuum the sludge from the bottom and put some shade over the pond to decrease the algae growth. You can put some quilt batting in front of the filter to catch some of the particles. It sounds like that would fill very quickly and would need cleaning pretty often.

The pond sounds polluted, and although many are opposed to water changes, it might be a good idea to change out at least some of that polluted water. Personally, I'm on the other side of that fence and feel that regular water changes are good for a pond.

What are your water parameters?

 

[poconojoe]

You said you have two UV lights.
I'm not a big fan of UV lights, but they can be a quick temporary fix.

I don't know how old your's are, but the bulbs inside of those need to be changed quite often. They suggest every year I believe.
Even though they are lit and look good to us, they lose there potency.

There are some people that like them and some that don't.

 

[j.w]

@Tony Gutteridge

 

[Lisak1]

I agree with @WaterGardener - while regular water changes are not my thing, in this case (dirty smelly water and small-ish pond) a series of water changes could improve your situation quickly.

THEN as mentioned you need to address the why - you have too many fish in too small of water volume. If you don't address that situation nature will take care of it for you... and that's always sad. New homes for a bunch of your fish (especially that big guy) will make the situation better for all of them. And make your pond source of joy for you as well.

Or you can go the route of more filtration, if you prefer. In either case your pond is telling you that it needs a bit of help to regain some balance. Good luck! And welcome to the GPF!

 

[mgmine]

As others have said get rid of some fish including the big carp. The filters probably need a good cleaning and depending on what type of filters they are replace the filter material. If you can see fine dust floating in the water then you will need to filter that out as the water gardener pointed out. The UV lights should solve the problem. IF they aren't then they should be replaced. Either the bulbs are bad or they are too low of a wattage. My guess is that the bulbs are bad or maybe the lights just aren't working.