I monitor my water almost daily. I do not let any of the perimeters get high. I do weekly water changes. I have the light set for only about 8 hours a day and took out all the items I had in there for decorations. It seems to be a little better. I have a big girl a 20 inch butterfly koi that is in a 125 and have algae but no big deal. The brown algae is just really ugly and it is kind of a new tank. I would say it is about 2 months old now. I have 2 of the sponge filters I bought for you in it as well as 2 hang on back filters. It is a 45 gallon tank with 8 baby butterfly koi in it I got from Japan. Beautiful little babies. The diversity in their colors are amazing to me. They are all about 4 inches long. I do know about goldfish being kinda dirty but, are Koi considered the same? I am currently growing them out to possibly sell them in the future. I am in the process of building a sump for the tanks and your videos are amazing and a lot of help. I disabled so cannot afford to go out and buy sumps for all my tanks. I will get a picture posted as soon as I can take one. I do have a short video of them all on my Facebook page.