If you have fish in the tank, the pepp needs nothing special over and above what they are fed. All shrimp species are great scavengers and do not require special attention. I would also not use foods like brine for anything in a marine set up. They are very lacking in nutrition for most types of SW
animals unless fortified with vitamins. The pepp will be fine with whatever foods are added in general.
If you end up using the brine, make sure you allow it to thaw in some RO
water and strain it prior to feeding (sparingly) to help remove PO4
and other impurities.