I was curious if the 3% hydrogen peroxide treatment would work for hair algae? I have a 20 gallon tank that I added new plants too. I originally just had anubias plants so no need to fertilize. I added some water sprite(Ceratopteris thalictroides) at the end of March. It started to grow but then hasn't done much since though there is a small amount of growth on it. At the end of May I added some crypt wendtii(1), crypt retrospiralis(11), corkscrew val(1), and dwarf sag(3). All but the retrospiralis came from another tank that had cyanobacteria. The wendtii was growing great but others kept getting covered. Anyway...the retrospiralis came from eBay. Great looking plants. I added a couple of flourish root tabs and a dose of aqueon liquid plant food. After this I started seeing hair algae. This happened in my other tank too before the cyanobacteria took over. I think this may have been caused by my liquid fertilizer. There was a ton of it in my small tank but I think the cyanobacteria caused it to go away. I don't think I spread it with the plants. Inhad them floating in the 20 gallon before I planted them for around a week or so. I was waiting on my retrospiralis to come in to plant everything at once. I noticed the hair algae soon after dosing the tank. It hasn't really taken over much except it's choking my water sprite and killing it. They have a bunch of gunk on them. There are also some threads on my spray bar. I also have a reddish brown algae appear in my anubias plants and sides of tank(this was before adding the fertilizer but it hasn't let up. My bristlenose passed so I'm not sure if she had been keeping it at bay or not. I haven't gotten another one yet.) I'm just wondering if the liquid fertilizer put too many nutrients in my already hard well water(hard water deposits are on all fixtures in my house). the tank currently houses 7 black neon tetras and 3 glowlight tetras. Would 1 ml of hydrogen peroxide a gallon be ok to dose the tank with? Mostly asking because I just purchased a different type of water sprite (Ceratopteris cornuta) which is going to maybe recover from shipping in my small tank that the cyanobacteria just got cleared out of. (If it doesn't within a week the seller will ship more). I also bought some water lettuce. I want both to go into my 20 gallon but I don't want the hair algae to kill them like the other water sprite. I have both in a plastic container with a heater at the moment until I move the water sprite to the small tank(5 gallon betta tank) in the morning(maybe with a thing or two of the water lettuce) but I just dont know about putting the water lettuce in the 20 yet. I saved some of the current water sprite in the 20 and put a couple sprigs of that in the small tank. Have roots on one and no hair algae either. Any help is much appreciated! And sorry for the somewhat rambling post, haven't slept in over 24 hours....too much life happens sometimes!