Almost 100% positive they do, I was looking at them the other day
I did some looking and it seems like most 30 gallon filters are typically for fish tanks. I don't know if they have anything that small. They may have one that works for 200 gallons or less. The best thing to do is call and speak to someone in the garden center. They may be able to order something for you or direct you to the right place to find that filter.
That place is incredible they would probably have it they have everything else you could ever imagine for a hardware store
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