Actually, I
hate HOB filters but in the case of a 1.3 gallon tank I didn't think a mini submersible would fit well. A small, weak, silent water pump sounds like my best option.
The Rio Mini 180 is 120 gph.
Rio Mini 50 is 66 gph before attachments. 2.2" x 1.4" x 1.8". Same size as the 180 according to what I've
read . Adjustable valve for flow rates.
Sounding pretty good if it's quiet. I could reduce the flow and then aim it to bounce off a wall or two and probably not have rip current probs. I've heard of reliability probs with Rios but in this application I don't think it would really matter. How quiet are Rio pumps?