Help green tank

[Firstman]

I have set up this small tank for a friend in San Angelo but his water keeps turning green. I don't know why. It's not hair algae it's just lime green the chem. is good all levels good I don't have the lights on much either there t5 and placed new bulbs even cut back time. I even taken everything out including water I started over and still it ended up turning again. I am not using RO machine we get the water from the store. The thing is inthe next room he has a fresh water tank and it very clear. I don't know what's up. Please help the only thing I can think of is the water quality. But we use the same for the fresh water. I have a skimmer and uv plus live rock in sump and in display a good amount. This is fustrating even the fish u can't see.

[kkiel02]

If it is just the water turning green what we did with my neighbors is to run carbon in a reactor, 3 days of darkness and did a 50% wc. I would just buy a ro/di unit for him though. That store water isn't as reliable because you don't know when they changed their filters. Also skim wet.

[BBQHILLBILLY]

I was thinking you had a dirty canister filter but you have a sump.
Ive seen green water in turtle tanks . . . . bad filtration somewhere, not sure

[jcnkt_ellis]

Not pure enough water is most likely the culprit for the algae bloom. Freshwater tanks have a different biosphere and can handle more iron, phosphates, and other trace elements that cause a green algae bloom like your friend is having. It's like comparing apples to oranges there. It will take time, a lot of water changes with good pure water, and probably running something like carbon to take out the trace elements and clear up the water. The algae bloom will persist until it starves...