This is a discussion on Filters for 55 gallon within the Freshwater and Tropical Fish forums, part of the Freshwater Fish and Aquariums category; -->
Would it be better to run two 55 gallon whisper systems in my 55 gallon or 1 cascade 1000 canister filter which filters 100 ...
There is only so much that can be said without knowing your stock. Some advice though, Tetra filters are very low quality and can develop a bad rattle over time. If you are going to look into getting an HOB look for something higher quality.
True, we need to know the intended fish. But having read your other threads on the 55g, I will jump the gun and assume this is intended for angelfish and shoals of tetra and corys. So a canister rated to a 55g would be better in my view. You will also have plants, floating and perhaps substrate-rooted, no doubt.
The canister (pretty much no matter the make) allows more options in water outflow, the HOB really only has one, "waterfall", although it can be baffled if needed, sort of. Canisters will generally last longer than HOB as well, for various reasons some having to do with design.
I use a DIY spraybar mounted vertically... but you could put multiple outputs, drilled spray bar or even one direct pipe out to set up what ever circulation and current that you might want.
I assume that the "1000" in the model number is 1000 gallons per hour... Probably overkill unless you need a lot of turnover for messy fish.