Pond water green algae

[tharriso]

Hey ph I have 5000l pond with small goldfish koi etc.
The water is not very clear at all green.
The filter has a 11w uv clarifier in it.

Last week I added a massive 72w uv clarifier. It has made no difference at all.

I have used those green water treatments they are fantastic but return to normal within a week.

Any pond experts got advice for this?

[tharriso]

Thanks

No more than half of the pond is in sunlight at midday. A third is covered with lily pads.

The filter says oase 6000, so assume that's meant for 6000l?

The pump is 65l/h 55w.

[tharriso]

spikeyhead said:

That sounds a tiny pump for a pond of that size, unless it's set up with lots of plants and bugger all fish.

I was thinking that myself, I think it might mean 6,500L/H ? It is 55W so would have to be horribly inefficient to only push 65l/h. It was bought as a package with the filter. Definitely says 65l/h though.

Anyway I have just bought a 18,000l/h pump off ebay, see what happens.

[tharriso]

W12GT said:

The mechanical filter needs cleaning regularly to prevent it becoming blocked

Not sure when this was last done might do it tonight thank you.

W12GT said:

The pump you have bought sounds too big; way too big. The aim is to turn the water volume over once every 1-2hours. So a 5000 litre pond needs a pump that will do 2500-5000 litres. You will also need to check the maximum flow rate of the UV and the filter itself.

Can the water be over-filtered? Is it a problem? It has to pump about 2m high so I thought you need more power to do that?

W12GT said:

Buy a test kit and see what is going on in your pond:- I believe the nitrate and nitrite levels will be quite high which isn't good.

I testing every two weeks lately and the levels are always good I think the water is good but murky.

W12GT said:

Is it one of these?
http://mobile.oase-livingwater.com/en_GB/water-gar...

That sort yes not sure if that exact model but looks the same yes.

[tharriso]

otolith said:

A 2m head is quite high - a lot of pumps will lose a lot of output at that sort of height. Most manufacturers supply a table of output against height.

Do you measure it from the pump to the highest point out of the water? Or from the surface to the highest point above water?
The pump is about 1m submerged and filter is 1m above the water.

[tharriso]

Here is a couple of pics, hopefully I can show an improvement in a few weeks time.