Have you looked into adding any aeration? Aeration can pay big dividends in controlling algae, especially in an earthen bottom pond. There are also other things like dyes to help filter sunlight where your other aquatic plants are not. Our company helps a lot of people with large ponds control algae and w/out hazardous chemicals and one product talk to people about is GreenClean Pro as it is safe for all types of aquatic life. Combine that and some beneficial bacteria and you have a solid 1-2 punch for controlling the algae. As someone mentioned earlier, oxygen depletion can result if you kill too much algae too fast, however you also must realize if you kill algae and it is left to naturally decompose, it will simnly fuel another round of algae unless it is removed or broken down by bacteria. Here is a link that might be useful: Pond Algae Control

Patrick, well, you certainly are an arrogant one, aren't you?? So I'll have to study for wild carp for decades before I am equal to you?? Gosh, you must be REALLY old!!! You really make me laugh. First of all.....why does studying wild carp mean that you are an expert on koi? As I said before....a koi is NOT the same as a wild carp any more than a poodle is the same as a wolf. And I do not tell people to take the plants out of their ponds, I tell them to not put koi into tiny ponds that are not suited to them. Koi are not the same as goldfish. They are large and dirty and putting plants in the pond will not change that one little bit. OK...to put it in perspective, lets say someone built a tiny little pasture and planted some lush grass for a few Shetland ponies. then they saw some adorable little Clydesdale colts. Well, they are small, they will fit nicely!! So in they go. The only problem is the Clydesdale colts do not stay small like the goldfish and soon they become too large for their environment. They overpower the lush grass and their waste piles up everywhere. Shetland ponies and Clydesdale are related, just like koi and goldfish are related, but the require different environments. I never once said that if you want koi, you must remove the plants. You are constantly twisting my words and I am getting really sick of it. If you will read back to the beginning of this thread, the original poster was advised by the koi BREEDER to take the plants out.....and I do agree. Ever see what a 36" koi can do to a water lily? It's not pretty. If you want to try to keep a water garden with koi, go for it!! I couldn't care less!! But it is unfair to try to cram a fish with the potential to grow to over 36" into a tiny plant-choked water garden. Ask ANY person who is serious about koi....people who keep expensive show-quality koi if they keep plants in their ponds. You will not find one. Koi hobbyists who are more concerned with the well-being of their koi put their emphasis on the koi, not the plants. I know a lot of people who give their koi 1000 gallons of water EACH. Do you think a koi would prefer to have room to swim in a good clean pond with good currents, or would it prefer to swim in a pond where it has to move slowly to avoid crashing into the nearest wall or rock pile? Basically it boils down to this. You do it your way, I will do it mine. I will continue to teach people what I know about proper koi keeping. Now go find someone else to harass. I am tired of your attitude.

I have a small 250 gal. pre form pond & I too have had success with using peroxide to keep the algae growth down. I use half a quart bottle of that WalMart 3% &dump it near where the water comes out of the Skippy filter (& make sure there are no fish directly where I dump!). I don't want the peroxide to kill the mint I have growing in the Skippy. I read to use this somewhere on this forum & it sure seems to work! I empty the filter in winter & toss the mint but I always have more in the herb bed to use the next year! I put the peroxide after it comes out of the filter as I didn't want to harm the filter/mint system in the Skippy. Have had clear water now for the past two years & only the short green stuff that clings to the pond sides that the fish love to nibble at. Thank you Jill for verifying the use of peroxide!!

If you have debris going back to the pool you have either a bad grid or the manifold is cracked. My suggestion would be to drain and start over. Take the filter apart and inspect the grids and the manifold as well a the debris scren on top of the manifold. You can try to chemically treat and vacuum to waste if you have a multiport but if it is that far gone you may be spinning your wheels and could cost a whole lot more in the end. Good luck