I posted this on another forum... should fit in nicely under this subject...
Subject: I fixed my green water...
Well, almost. I'd say I'm about 70% there. How did I do it? Mainly patience. And a few other things. I'm putting this out there hoping that others will read it and take some inspiration from it... I've lurked on a few forums and read, and talked to my local pond shop, and here is what worked, as it is a combination of a bunch of methods.
First, load up on patience. Without it, your pond will stay green forever. Mine was peasoup three weeks ago and I was contemplating tearing it down because it was so frustrating. I couldn't see the fish, and have no clue how they can live in such conditions.
Anyway, my setup is a biofalls, a 15 watt UV, a 1250 GPH pump, in an 850 gallon pond, and about a dozen decent sized fish. Everything pretty much said 'avoid a water change because the problem will come right back,' so I started a pretty agressive treatment, some against the rules, but it seems to be working.
First, AlgaeFix... the recommended dose. I turned off the UV, and added Organic Digester. I left the UV off for three days to allow the bacteria in the digester to take hold. I washed the filter pad every six to eight hours to get rid of the dead algae. I also put in a ballcock to slow down the water flow to the falls, as the pump is 1250 GPH, and the 15 watt UV is only rated for 1100 GPH flow rate... why the dealer sold it to me that way is beyond me.
On the third day, I plugged in the UV and dosed the pond again with AlgaeFix (same dose) and the recommended dose of Organic Digester, all the while rinsing the pad. I dose every three days, and for the fourth dose, I unplugged the UV for two days. I am on my fifth dose and can see the bottom of the pond (18 inches down). No longer is the algae suspended, and it appears that the fish aren't stirring it up anymore.
I still clean the filter pad every six to eight hours though, but it isn't nearly as bad as it was... I think a couple of more days and I should be good.
Not sure if this helps anyone, but I hope it does. It seemed to work for me... patience again is the main ingredient.