Will raising mag. work for this type?

Well at this time i dont have a phos reactor (maybe with tax money) yea i have coral open brain, tongue, few leathers, GSPs. feeding is very light as i only have 3 fish and its maybe 2 or 3 times a week (more often since i got my tang which i shouldnt have gotten i know) and its very very little. Lights are on 8 hrs a day 400 watt mh and 4 65 watt pcs and they do need replaced. i have a 90 gal. tank with a 30 gal. sump/fuge with cheato and a 3 inch sand bed in fuge part. skimmer is under rated as i upgraded my tank after i got it its a coralife super skimmer 65. Times are rough right at the moment, when i got into this hobby i was promised 50 hours a week or more and now im down to 40 hours and a very tight budget.

I need to do somethin bout it, its ugly looking.