Hello my Axolotl, Mel is in a 20 gallon long tank. I have a 10 gallon regular filter and a sponge filter. I do have the water pretty high because of the regular filter. I recently put duckweed at the top of my tank. Since then the regular filter has created a lot of movement from the duck weed. I was wondering if the regular filter need to be on all the time. It seems to get some of the floating plant I have in it stuck and I'm always messing with it. I did shut off the regular filter and kept the sponge filter on. Before I did that Mel was moving all over the place (they are a juvenile) now that I turned it off Mel has calmed down. I'm not sure if keeping it off is okay.