Certain foods like frozen Formula 1 and 2 as well as other gelled foods are impossible to rinse well. I stay away from them. I'm assuming Marine Cuisine is similar? I don't know that one. I also stay away from the foods that are blended.
I only use whole animal frozen foods like mysis, rotifers and Cyclopeeze. I put 1 ml Selcon, 1/2 teaspoon Zoe and 1/2 teaspoon of Marine C in a shot glass and mix it together. Then I take 1/2 teaspoon of this mix and put it in little plate. The seaweeds and flake soak in the plate. 1 cube of frozen food defrosts in the shot glass. After everything is defrosted, I pour it into a brine shrimp net. Then I pour either ro/di or tank water through the food, moving it around with my fingers. The seaweeds go from the vitamins to the tank without being rinsed.
I'm not saying my feeding regiment is perfect, but I'm comfortable with 24 fat fish in a 180 gallon that has a DSB and 0.01 PO4 and undetectable NO3 (my NO3 test kit is not the best).