Pond water green algae
Discussion
An appropriately powerful UV unit matched to an appropriate flow rate will kill algae, as well as flocculating them, but if you don't have effective solids removal you'll just be pumping the stuff round in circles as it rots - and if your water remains murky, the exposure of remaining live cells to the UV as it passes through the tube is going to be reduced and may not be able to overcome the rate it is reproducing at.
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.
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.
RichB said:
That's what known as a canister filter/pressurised filter and generally they are now considered as good as the open gravity filters however because you can bury them that are popular. I have a 6,500 ltr pond with koi, goldfish, tench and orfe and MrsB more or less insisted on a canister filter that could be hidden. For 6,500 ltrs I bought the Oase 30,000 filter on the basis that you should double the number if the pond is in sun and double it again if it has koi. And, even with that size filter I struggle with murky water. The other problem I have is that I can't have oxygenators or much plant life because the koi just eat it. They will polish off 25 quids worth of elodia in a few days, and that's an expensive salad bar! IF you don't have koi I would chuck in tons of elodia and hornwort.
Have you thought about an air pump?
http://www.absolute-koi.com/cat3.html
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.
myvision said:
RichB said:
That's what known as a canister filter/pressurised filter and generally they are now considered as good as the open gravity filters however because you can bury them that are popular. I have a 6,500 ltr pond with koi, goldfish, tench and orfe and MrsB more or less insisted on a canister filter that could be hidden. For 6,500 ltrs I bought the Oase 30,000 filter on the basis that you should double the number if the pond is in sun and double it again if it has koi. And, even with that size filter I struggle with murky water. The other problem I have is that I can't have oxygenators or much plant life because the koi just eat it. They will polish off 25 quids worth of elodia in a few days, and that's an expensive salad bar! IF you don't have koi I would chuck in tons of elodia and hornwort.
Have you thought about an air pump?http://www.absolute-koi.com/cat3.html
otolith said:
Ideally, you want another shallow pond through which you pump the water, fill it with gravel and plant it with reeds, iris, watercress, etc.
Ah, an outdoor equivalent of a refugium. Like it. I wonder if you could even have a bog garden as that function? I've always fancied having a bog/marsh garden ( for flag Iris etc ). 
RichB said:
That doesn't look too bad to me, how clear do you want it?
Incidentally, are you sure that's 5000 ltrs?
That was my first thought too. It looks like railway sleeper edging which would mean a maximum width of 8ft by 6 then the little corner of 2ft by 2ft. That equates to around 1500 litres per foot of depth. Incidentally, are you sure that's 5000 ltrs?
How deep is it?
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