i have my 3 gallon pico and a frag of PPEs that came over to it had hair algae and now its spreading. i have 1 head of frogspawn 2 candy canes and a mushroom rock in there as well.

if i cut my light cycle for 3-4 days, like ive read to do to control hair algae....will my corals be okay or should i move them back to my main tank?

what in your tank is giving nutrients for the HA, lighting could be reduced that would help, clean off as much as you can, do a water change, depends on what is growing the HA

From what ive been told as Im going through the same problem right now, is to look at your phospate levels.

its a new tank. i brought it into the tank on a frag. i just build my refugium a week ago so im hoping itll do some nutrient removal. lowering my lgihting schedule...okay....but should i go a day or 2 with no lights?

anyone else chime in?

I have gone 3 days with no light without any ill effects. Try doing more frequent water changes, and physically removing the hair algae.

3 days without light isn't going to hurt your corals. As long as you make sure NO light gets into the tank, and I mean no, cover it with something just turning off the lights isn't going to work, the hair algae should die.

This will mean that the nutrients bound in the algae will be released into the water so unless you find a way to remove them, like a couple of big water changes, it'll just fuel further algae growth a few days later.

Turning the lights out for 3 days will definitly not be a problem. but that is only the start. you must find out where the nutrients are coming from. Do you rinse your food that you feed the fish with ro water. Once I started doing that in my tank it got rid of the hair algae. Is your cuc large enough. refugium will definitely help. manual removal of hair algae is a must. Increase your water change amounts until you get it under control. Don't let it get you down the tank sounds like it is still a new one. Good Luck