This is my experience with Selcon.. And thanks to FSN for suggesting it back when..
My process is that I thaw the food, rince twice in RO water then place food back into saltwater with Selcon .5 ml every third day. I haven't noticed an increase in any nutrients in my system in fact I have been happily experiencing a 0 nitrate reading for a while.
But thats not to say in other systems it couldn't increase the nutrients.
The best thing I have noticed is the overall color and health of all the livestock in my tank.. No one seems faded or whitish looking at all.. Colors just pop and thats even under my t5's and not my 14k's.
JME