I was reading about how healthy spirulina is for all fish and I was amazed at how beneficial it is, I want to get the pure powder form rather than the tablets you can buy that have other stuff mixed in them but I can't figure out how I'd feed the powder to my fish? Won't it just dissolve and get the water all dirty?

I don't *think* it would make a mess as long as you don't feed too much at once, and you should probably also turn off the filter or anything else disturbing the water when you go to feed it. This way the spirulina doesn't go all over the place with the water movement.