The problem of holding pressure shouldn't be a problem as long as you don't restrict the output from the bucket. They have really nice seals and I was wondering this same thing. Instead of using a pressurized container, I ended up using an up-flow design that hangs on the edge of the tank. I also use a carbon cartridge in a "whole house filter". I put some garden hose adapters on it to make it portable. The only problem with carbon cartridges is their useful life is only about a quarter of what they are advertised for (evidenced by my water tests). If you carbon for water changes, buy a chlorine test kit for swimming pools. They start at $5 so there is no reason for everyone not to use one in their routine.