You may want to place the ammonia source (shrimp) in a nylon bag or nylon hose. After a while it will breakdown and this way you won't have rotten carcass bit scattered about the tank.
I've often wondered how well using pure ammonia would work in lieu of the shrimp. Much less smellier for sure. You definitely need to use ammonia that is free of dyes, perfumes, surfactants, and detergents if you choose this route. That's what I use for FW
I've not operated a protein skimmer before but from I gather, the device should generate foam that will rise up the column and a small portion will spill out into the collection cup. The cup should be emptied periodically. And I think there is a desired consistency of foam you want to generate; not too dry and not too wet. I could be wrong. Protein skimmers are not very effective in the fresh water aquarium.
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