[Clerk]

If the filter has two parts only replace one at a time. Alternatively, you can turn any of these HOB filters into a hybrid aquaclear style. Meaning, you can just buy aquaclear (or any other media in a bag), and stack it in the box. I usually used two sponges and some biomax.

I have done this with several filters before I switched to canisters. The sponges can last up to a year, just rinse them in tank water every few weeks or so (more if tank is planted.) The biomax lasts at least 6 months, just rise in tank water during your water change. This way you lose very little bacteria, and save money on filter inserts.


But, if your current filter insert has two pieces that can be changed independently (Filter floss/carbon and a carbon sponge) this process is not needed.

The only danger comes if its all one peice, then you lose the majority of your bacteria, and your tank may go though a mini-cycle, which is dangerous for your fish.