I’m also in an apt and like the 12 gallon totes from Costco. I mix 9 gallons at a time cause I wouldn’t want to fill it to the top. Then I can do 2 4.5 gal water changes. Just a bit larger than the bucket. I like that they stack so I store them in a closet with sw in one and then stack another on top with assorted pumps and reefing stuff
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Oh! That’s a great idea! Unfortunately, I’m keeping my tank in my office, which does not have room for totes that big. For now, the 5 gallon buckets are working well.