I'm not sure if this is the appropriate thread to post this question....however, technically algae is a plant so here goes. I have a 1200 gallon pond that gets full sun most of the day, I have 6 very young koi about an inch and a half long. The pond is just over a year old. About once every two weeks I do a 20% water change, put in beneficial bacteria (I can't remember the name of the product but its from Microblift is purple and smells terrible) and a detoxifier that removes ammonia, nitrites, and nitrates. I used to use an algacide to keep the algae down. I had read that trapdoor snails are good to help control algae and I thought they would add some interest in my pond. Since then, I've seen varying reviews on that. Never the less, I now have 50 trapdoor snails in my pond. Ok now that you have all the particulars, time for the question. I'm getting a lot of this really powdery looking green algae looking stuff laying on the bottom of my pond and what I'm assuming is string or hair algae growing on the sides and on some of the rocks. While I can see the snails going to town on this stuff, they aren't getting it all. I don't want to kill or remove the snails. Is there any algaecide that I can use that will not kill my snails? Thanks in advance!