Filter Cleaning

The frequency of cleaning depends mostly on how much waste it deals with so basically depends on how many fish you have. If you are fully stocked it will require more frequent maintenance. I would advise checking the sponges one month after the last clean, and if the sponges aren't quite heavily gunked up then leave the next one for maybe 6-8 weeks...

Over feeding the fish leads to build up of decomposing uneaten food and if you have liv plants there may be rotting vegetation there too so all of these factors will affect the build up of filter sludge.

A gentle swish and squeeze in old tank water is all that's required, do not rinse under the cold tap. Just in case you didn't know.

Regarding external filters, you might be interested in a YouTube guy called Pond guru. He has some excellent advice and in particular he gives amazing tips on how to "Pimp your filter" basically giving a complete lesson on how to best set up your filter sponges and media to optimise your filters performance. Link below

#Invalid YouTube Link include https#

You can stop fry from getting into the filter by using a prefilter on the tube that takes water out of the tank, or by making a slit in a sponge and pushing the end of the tube into that.