I can get a good solid layer ~1" thick after a snake packs it down in a 52 at hefty tub (slightly larger than a 41qt) and it takes a bit under 1 bag to do 2 tubs. Probably do about 2.5 tubs of my size tub, 3 if you use less thick of a layer or have big water bowls that you don't put substrate beneath.
I don't have anyone in a 28qt, so not sure how much that takes.
I do find that I don't need to do a complete clean as often as other sunstrates; if I do spot cleaning well, it still smells fresh at 2 months. (And it contains pee to smaller area)
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