oh, wow, that is way to much food! Most people only feed every other day and sparingly also. That is surely the source of your nitrates. Also, it's a good idea to rinse frozen food in RO
water beforehand as the water they are frozen in contains nitrates also.
I know it may seem strange at first to only feed every other day, but your fish will be just fine and you can get your nitrates under control easier and faster.
Also, brine shrimp is like potato chips for fish--not much nutritional value.