Green hair, bubble, red slime, etc...new tanks...

[Sk8r]

1. green hair algae: usually the first blush of life after cycle: why? Too much phosphate. Never mind testing. It either comes in with water that wasn't ro/di, or it soaks (leaches) out of uncured rock or sand. Obviously, use ro/di. But if it's slowly leaching into the water from the rock, you'll never catch it on a test. The algae is sucking it all up and using it.
What can you do? Old toothbrush, wind, yank, toss. That will 'export' the phosphate in a very direct way. Very few fish will eat it, and those that do just poo the phosphate right back into the water. What WILL get it is GFO, in a reactor (about 50.00) ---Granulated Ferric Oxide will absorb it: if it's real bad, it'll absorb all it can take in a week and then do nothing but sit there. Unfortunately there's no "I'm full up" signal that flashes: this makes it a good idea to change the medium out once a month until the problem shows signs of easing. When you toss the old medium, you're tossing a lot of phosphate that will never trouble you again. EVENTUALLY the rocks run out of it and you'll never see it again.
2. bubble algae, aka valonia: again, pops up now and again. You'll hear a lot about getting a mithrax crab to eat it (he'd rather dine on most anything else)...and never ever to break the bubbles because it releases spores. Well, I've yet to see a crab eat bubbles without breaking them, but there you are. The problem will eventually go away. I've seen a few tanks where it got epic, but in a tank with well-balanced chemistry (salinity 1.024, alkalinity 8.3, calcium 420, magnesium 1350) it's usually a non-issue. You'll find visitors love it and think it quite pretty. Tank owners have other words for it. But generally, don't sweat this one unless it promises to get really bad. Then toothbrush scrubbing some rocks may be in order.
3. red slime, aka cyanobacteria---is, surprise, not algae. It's usually the third thing to appear in a new tank, and again, if your water chemistry is good, usually it isn't a problem. It's a red blush on the sand that can proceed to a quarter inch thick blanket of bubble (oxygen) producing slime that covers corals and everything. THe good news is that it's generally harmless except for blocking the light. Blow it off with a turkey baster and the corals are not hurt.
It appears often when stray sunlight hits your tank as seasons progress and that spot of sun creeps toward your tank glass. It loves that kind of 'off' lighting. It can pop up when your lights are getting old or your lighting is wonky for whatever reason. It may be a near permanent resident in a lighted fuge, with no particular problem.
The cure is turning your lights out for 3 days, followed by a day of twilight to let corals and fish wake up as they would after a storm front on the reef. Meanwhile you should tend your skimmer carefully and make sure it's doing its best, which is how the nutrients (spare amino acids) leave your tank. It's living on a little too much richness of carbon and a lighting it likes. YOu may have to repeat the lights-out every 3 weeks or so to see the last of it.
I don't advise the chemical solution to this: I tried it once and ended up drastically lowering my copepod population, which proved quite expensive, with a mandarin to feed; and I noticed other deleterious effects as well. I have also known people to have more significant issues, particularly if they used the chemical solution with an inadequate skimmer: dead stuff piled up with nowhere to go. The lights-out is slower, but is gentler on the tank. Do you need a skimmer: pretty well---yes. You do.