I started with conventional canister filters: Eheim, Fluval, etc. but at one point, I jumped the gap and switched to a sump!
The inspiration was the koi pond area, and the challenge was to adapt such system to way smaller volume.
After 8 months of development (well, only week-ends over this period..) and 5 prototypes, I finally get a full functional and automated system with optimal modules:
Roll paper filter for mechanical filtration
Moving bed (Helix Micro) for biological filtration
Cartridges (Seachem Purigen, Arka Phos-Out 4 and Sili-Out 2) for chemical filtration
You'll find all the information on a dedicated websites:
Automated aquarium -> https://www.miaquarium.com
DIY fresh water sump -> https://www.diyaquariumfilters.com
Other interesting references
I point here out filters that I experienced myself and would suggest with no doubt. Of course, and hopefully, you can find way more brand and model, e.g. Eheim or ADA, but there is no point here to list exhaustively or compare intensively these alternatives. With my experience, I'm convinced these 2 following filters are currently the most interesting systems.
One of the biggest if not the biggest canister filters you can find for standard (big) aquarium., with an incredible water flow. Filter media organisation, at least pre-filter pads, is quite original. It is really robust and simple by design, you can unbuild the pump to take away any gravel that may block the propeller. An extra valve at the bottom of the filter help to do water changes. You may tune it as I did with polishing pad layer and especially other bio filter media e.g. Seachem Purigen.
This version includes a heating unit, no need to get an extra element in your tank or inline for that mater, and especially a pre-filter module very easy to extract and wash separately from the rest of the filter. Oase certainly touch here the sweet point for many fish keepers and now it is one if not the reference for most of aquascaping tanks. Interestingly you can pick 3 different color for 3 different foam coarse (30 ppi, fine 45 ppi, ultra-fine 60 ppi) that make handy the water polishing. You can here as well change the bio filter media given by default.
Complementary to the filter itself, maybe even more important, here are some filter media that worth to be considered to replace default media you receive with a filter.
Quite famous biological filter with one if not the highest porosity or surface area (>~700 m2/L), exactly what you're looking for hosting the maximum of nitrogen cycle bacteria.
Alternative to Seachem Matrix that I'm experimenting lately. Here as well huge surface area (3200 m2/L), but more interesting are both version soft and hard that seems to impact the pH.
Another product well known from Seachem, this absorber remove organic material before its degradation, therefor helps to get slightly less nitrate NO3 at the end. But it is especially an efficient water clarifier, removing tanins water coloration. It can be regenerated with household bleach a few times.
Phosphate PO4 is way easier to extract than NO3, and remove this element from water helps to control algae development, especially if your tank is not such planted.
Quite interesting absorber of silicate, phosphate, barium, arsenic, chromium, as well as dyes and turbidities. The shape small marble limit material clogging. Removing Silica SiO2 helps to prevent brown algae (Diatoms), especially when at start.