How often do you clean out your sponge filter? and do you ever change the sponge or just keep cleaning it?
i squeeze mine out with every water change till it looks cleaner....and replace when it falls apart (yet to happen)
Since I don't use my sponges for mechanical filtration (they are just for added bio) I don't clean them out very often. Maybe once every couple months, depending on stock. They just need them to be clean enough to still have water flowing through them if you're just using them as back up and additional bio IMO.
If you're using only sponge filters to run a tank, you want to clean them more often.
I have 2 aqua clear 110's on my 85. I altenate rinsing the sponges out weekly with cold tap water. I will replace the sponges as they fall apart. I know everyone one says you should use old tank water for rinseing but my 85 has been set up for 14 years so it is pretty established.
Why chance killing off bacteria and depleting what bio you already have built up?