[JimE]

The more I read, the more I know, the dumber I feel!
I really like canisters for multiple reasons; one brand even has pre-filter that can be cleaned without opening biological (main) section and a built in heater.
But I also see big advantage to increased water volume by using sump.
Which leads me to considering a homemade large volume canister-like sump.

after reading multiple posts, you Tubs etc. it seems biological media is another moving target:
Almost seems to me, with enough surface area on mechanical filters, (additional) biological media not needed ?

like some videos showing sponge filters as the only filter combination of mechanical and biological....

which brings me back to water changes.

would it be fair to say, the more frequent the change and the more volume of change, the less need for elaborate larger biological media capacity?

 

[shrimp? fish? CRABS?!?]

I can relate, but I've heard a lot ALOT o people use sumps as it seems like there is jus two much area for bacteria to grow on to, but unless you have large tank I (prob 75 & up) you will be fine with a canister filter if you willing to deal with that, maybe I'm just a consumer getting scammed by companies but I feel like biological media is needed. (take this advice with a grain of salt as I don't have a lot of experience in this hobby, (less the a year) but I do research and enjoy this hobby). so if someone else comes along and comment here, listen to them

 

[minorhero]

Sumps are good because they are easy to work with and have unlimited ability to expand. What do I mean by that? Well as an example I'm planning out my UNS 120P right now. One area of concern I have is the heater. I will be using a canister filter and I do not want the heater in the tank, so I pretty much have no choice but to use an inline heater of which there are very few brands to choose from and most have serious flaws. If I had a sump I could just buy any heater on the market and stick it in the sump. I could even buy multiple small heaters and put them in etc. I also need a thermostat to make sure my heater doesn't break and cook my fish. I will need to make a crazy waterproof inline holder for my probe for my tank, but if I had a sump I could just drape the temp probe over the edge of the sump and it would work perfectly. I plan to use an auto doser for ferts in my tank. So I need to make some wacky contraption to inject my ferts inline with the return and just hope my check valves don't break because then either I flood my house or my ferts overdose/underdose and I have dead fish or algae outbreaks. If I had a sump I could just drape the lines over the edge of the sump and be good to go.

Sumps are bad because they require you to drill a tank. I don't want to drill my tank because I am hoping to enter it into an aquascaping contest and I can't have an overflow or similar mucking up the picture.

But I really wish I could just use a sump.

Canister filters work because they are completely sealed and to a limited extent, pressurized. If you wanted to make a canister filter the size of a sump you would need a way to pressurize the entire thing... I do not recommend this, it sounds like a giant disaster. Also cleaning it sounds like a horror show. I physically pick up my canister filters and either clean them outside or in the sink. If you had a 40 gallon canister filter... yeah you couldn't do that.

As for biological filter media... Well I used to believe it was more than marketing hype.. I now believe differently.

You need surface area for bacteria to grow on. That surface area does not need to be something that an aquarium company wrote 'biological media' on. Bacteria don't care. They will grow on anything. My favorite media for my canister filters is sponge. It lasts forever, can be cleaned by wringing it out, does mechanical filtration just great, comes in different densities, is cheap, and will also host bacteria just like any other surface in the aquarium. Its difficult to have a planted tank and not have enough surface area for bacteria to successfully keep ammonia and nitrite under control for any reasonable (or even unreasonable) number of fish.

This a long way of saying, just cram your filter full of sponge and do a once weekly water change of 50+% to help with algae control.