I use distilled water for everything. It just removes one variable, at not much cost.(posted 8696 days ago)Why make up large amounts of PhotoFlo anyway? I mix a little more than needed for my tanks, and use it until I neeed to mix more, or it gets funky.
I do a last rinse in distilled water after washing, then into PhotoFlo (going to try Edwal LFN) mixed in distilled water.