Brown water or brown algae

[Plynpool]

I have a 45 gallon with 10 baby koi. They are all healthy. Well at least they swim around like they are at least. I am currently working on moving a few of them to my 55, 125 and 2 30 gallon tanks. I am really wondering why my water is brown looking. It also looks like there is some brown algae forming on some of the things I have in the tank. I have a considerable investment in these little jewels. There colors are amazing. I have only have them 10 days and at first I would come into my room and they all run and hide. Not now all 10 at the font looking at me I guess. Food you goof. Feed us. I have one Butterfly Koi that is about 18 inches. It amazes me how interactive with me she is. Her tank water is crystal clear. I also have bio filtration on her tank and do water changes about every 7-10 days. She is one awesome and beautiful fish. The brown water is really unsightly. Any ideas would be greatly appreciated as to what caused all this.  Godspeed to all. 

[Cory]

What are your current water parameters? Do you have a picture of the tank? How long is the light timer set for? 

[Plynpool]

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. 

[Colu]

I think koi are are causeing your  algae problem you could be getting some free floating algae or the constant action of the fish is stirring up the dirt in your grave koi produce a lot of waste  for a 45 I halve the amount of fish in that tank or increase filtration

Edited February 6, 2021 by Colu