Several reasons. Easier water changes, heater placement, if I install a light, nursery for fish and plants, extra biological filtration, and, an easy way to hook in line CO2.
30 years ago this was an easy way to filter heavy waste producing animals ( aka cichlids, goldfish, catfish and carp).
This diy cost me under $100.
A commercial sump of this size would be around $300-400.
I'm hoping to give back to the current generation of aquatic keepers, what was every day back when I started.
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