hair algae on new setup

[kwirky]

My tank's at it's first week now. I'm running just the actinics (half of a 4 foot, 8 bulb T5 fixture).

It was set up with tap water. I had a diatom problem, then my RO/DI unit came in last friday. Did a 25% water change with RO/DI two days ago, which obbliterated the diatoms almost overnight, but now this hair algae's showing up.

the same thing cleared up in my nano within a week, but I'm more nervous about it in this setup, since my cleanup crew only consists of 5 trochus and a single blue legged hermit.

I'm figuring the tank's moving up the algae heirarchical ladder, but here's my tank specs ATM:

120 gallons
81F
nitrate: <= 0.2ppm (salifert kits are great!)
calcium: 450mg
euroreef RS135 skimmer skimming.

should I just sit tight, waiting until the tank's had more RO/DI water? I'm thinking of ~25% changes every week for the next month. is that overkill? I'm nervous about this tap water, since i WOULD like to turn the lights on full at SOME point...

on another note, anyone know how to make a euroreef skimm wet vs. dry, and which I should be skimming? heard it should "skim wet" but don't know how to get it to do that exactly, or if I'm doing it already.