Those mats do work well BTW.
There must be a dozen reincarnations of the Hamburger Mattenfilter in a dozen languages. These work very well.

It's odd more folks do not use such old school methods.
I use biomedia, anything with high surface area that I can clean once in awhile.
A sock micron filter bag.
Not much else.

Similar method for Marine systems, but either use a Skimmer or a refugium.

The guide at the bottom is an excellent list of links for folks interested in using sumps BTW.

"sump for a planted tank".



Regards,
Tom Barr