Hot filter

HOT Filter - Hang On Tank Filter. An External Filter which is hung on the tank. Some are not intended for permanent installation, but only for short-term use, and are placed in front or on the side of the tank.

For my BN/ABN breeding tanks, I have at least one big sponge, and a HOT filter in each tank. I alternate cleanings of these during the weekly water changes. For the breeding caves, I use homemade tile caves and they've proved excellent.
good luck ...