They work, but it should not be a long term thing for a fish tank. It is stressful on the fish and could block off the flow. But it works for that short time you need it.

It does divide the aquarium into 2 distinct sections, but I found that, although perforated, the water circulation between the 2 sides was relatively poor. This is a good temporary solution to a problem tank but NOT a permanent one. Do yourself a favor and just get another spare tank just in case.

------------------------------
8 tanks running now:
1x 220 gallon, 2x55 gallon, 1x40 gallon long, 1x29 gallon, 1x20 gallon long, 1x5.5 gallon, 1x2 gallon
Gouramis, barbs, rasboras, plecos, corys, tetras, fancy guppies, swordtails, ottos, rainbow shark, upside-down catfish, snails, and Max and Sparkles the bettas.

My findings were similar. Dividers can mess up the water flow considerably and so i wouldnt recommend them as a permanent solution in most cases.

------------------------------

Forum Rules Forum Etiquette
E-Book Salt Myths Fish Cycle Fishless Cycle
Goldfish Myths Fish Diseases
Tank Re-Seal Photo Guide

I wait until I see it on clearance. I don't use it except for short seperations during breeding or in a pinch while cleaning or moving other tanks.

Used it in my 10 gallon quarantine tank when adding two new fish of different species. Because it was a small tank the two fish did not get along. The pieces kept falling off while setting up, and the air stone's bubbles didn't reach the other side of the tank, even though it was placed right at the edge of the divider.