help with water please

93 gallon cube, set up March of 2012.

five fish:
pinkface wrasse
foxface lo
longnose hawkfish
2 clarkii clowns

coral: (all are frags)
xinas
mushrooms
rics
zoas
trumpets
duncan
frogspawn

invert:
carpet anemone

weekly 10 G water change
1.025 via refactometer
stable 78 degrees

Salifert:
cal - 450
alk - 9.5 dKh
mag - 1250

Hanna:
phos- 0.1

Red Sea:
phos- 0.06
Nitrite- 1.5

I feed two frozen cubes (thawed and rinsed) every other day, my light cycle is from a single Radion on natural mode, peeking out at 50%, from 8am to 10 pm.

I know that we would all like our NO3 and PO4 to be ZERO, but is that realistic? and if not, how close is good enough? Im not currently having an algae bloom, and haven't had one since the cycle process last march, but i do have a moderate dusting of diatoms on the sand bed. i do have a BRS duel reactor, which i dont use anymore, because my LFS says that SPS coral doesn't play well with GFO and that is my goal. id like to have my chemistry correct before i waste money on sps just to have them die off.
I know i need to get my NO3 and PO4 down, and i need to get my Alk up to around 10.8ish. my question is how?

 

The only concern with your water would be the phosphates i think. The nitrates aren't going to do much harm when that low. The only concern that i can think of when using GFO with sps would be lowering your phosphates too quickly. you will need to lower them slowly and then you shouldn't have a problem.

 

+1

Your LFS is not entirely correct. Some corals have serious issues with aluminum-based phosphate removers; GFO, OTOH, doesn't normally cause problems unless you introduce too much at once to an established system. If you start with 1/4 the recommended amount then slowly increase over a few weeks, you'll be fine.

BTW, you might do better at feeding 1 cube every day; IME it would result in less wasted food as fish will usually only eat for 2 or 3 minutes regardless.