BGA woes

[darkjedv]

So here's my stats:

30g tank (10 months old)
20lbs of live rock
4" sand substrate
Coralife super skimmer
Emperor 280 Filter
2 24" Nova Extreme T-5;
2-24 W 10,000°K, 2-24 W 460 nm actinic
MD7 pump with SCWD
temp: 78.0 F
SG - 1.025
Ph - 8.2
Alk - 4meq/L
NH2 - 0
N02 - 0
N03 - 5
Ca - 420
Phos - 0.1
Fish: Long Nose Butterfly, Royal Gramma, Dashed-Line Blenny, Ocellaris Clown
Coral: Evergreen starburst polyp, starburst polyps, green torch, pink zenia
Verts: 2 Skunk cleaner shrimp, 2 pom pom crabs, 5 conch, 10-12 hermits, brittle stars (hitchhikers), 2 small nudibranches (hitchhikers), 4 feather dusters, snails (hitchhikers).

So for a few months now I've been fighting the BGA in my tank. Been vacuuming it off the sand during water changes, 5 gal every week or so. Also been blowing it off the rock with a sea squirt. It seems like no matter how much work I do it always comes back. Mostly on the sand. I have the pvc pointing at most places in the tank to have a good water flow. I don't think I'm overfeeding, 1 cube of Hikari Mega-Marine in the morning with 5 drops of AminOmega, 1 cube of Hikari Mysis Shrimp at night with 5 drops of Zoe. 1 cap full every 2 weeks of Marine Snow. Everyone eats it quickly...in a few minutes. I went to the LFS to pickup some RO water, and asked some people about my BGA. One guy said he had the same problem and used Stress Zyme to fix it. He said it took a few weeks but worked. I'm very hesitant on dosing my tank with that since I've heard its snake oil and I don't want to buy anything that will harm my inverts or algae. Any suggestions? Do I have to just keep doing what I'm doing until it fades?

Thanks!!!