Dosing Amino Acids - SPS low nutrient system

My tank is almost entirely SPS and I'm currently running biopellets and GFO to keep nutrient levels low (NO3 is always 0 and PO4 hangs around .02-.04).  On a whim last November I ended up trying out Red Sea's Reef Colors and Reef Energy products - seem to be a cheaper American made version of some of the Zeovit products from Korallen Zucht.  Reef Colors are four seperate products which are essentially supplemental elements to enhance certain colors in SPS corals.  Reef Energy is a two parter with one to feed the corals disolved organic matter and the other is an amino acid and vitamin supplement. 
I was absolutely blown away with how much better my corals looked - deeper colors, crazy polyp extension all day long, and even better growth. I was very happy with the system for the last few months and then I ran out of Reef Energy.  When I went to go pick up more and they were out of stock... so I thought oh well, let's see how things go without dosing disolved organics and amino acids - perhaps my corals were looking so much better for some other reason.  This was definitely the reason things had improved.  Colors faded back out and polyp extension is horrid.  Nothing else had changed.. all parameters are well controlled and very stable.
I had some Zeovit products (Coral Vitalizer and Pohl's Extra Special) laying around that I'm currently using in the interim until I can find Reef Energy or some other alternative - the Zeovit products don't seem quite as effective and are much much more expensive.  Coralville Bay carries the other Red Sea products but hasn't had Reef Energy in for a month or so and Bulk Reef Supply appears the same way so I'm really hoping that product didn't get discontinued for some reason.
So my question for other SPS keepers out there with low nutrient environments, what if anything are you dosing and how have your results been?