Is there some particular benefit to the RO rinse vs. saltwater rinse ? I usually just thaw in tank water and drain in a net, then put on vitamin and garlic occasionally.

I don't have a lot of fish in my tank and I don't overfeed, so the food I make in the morning lasts for the afternoon feeding as well. Tankwater degrades the food quickly, even when stored in the fridge during the day, RO water does not.

I use RO water since it has no impurities to add to the food. That, plus the fact that I have the RO spigot on the sink in the laundry room where I prepare the food and the freezer containing the food is located. Everything is in the same location, so might as well go with the RO water.