It's most likely the needle valve that's giving you the problem. I had the same problem with my Korralin reactor. I solved the problem by tossing the needle valve and replacing it with one of those thumbwheel restrictors that are used on IV tubing.
If your tank is the same dimensions as my 220 (72x24x30) then three 175 watt 10,000K german bulbs with two 6 foot VHO actinics will give you a crisp clear tank without the noticable blue tint.
Yes I would also run the skimmer during curing, to remove the organics produced by the curing process. IMO your lighting should be good enough for the average 30 gal., but if you want to keep things like acroporas, and clams you might want to think about adding a 150 or 175 watt MH fixture as...
A lot would depend on the demensions of your 90. IMO a combination of 175 watt 10,000 K MH's (German bulbs)and Fluorescent VHO actinics give a nice crisp color to everything.
