Filtration For A Divided 20g Long

I'd like to try to consolidate some of my bettas into a 20 gallon long, divided in thirds, but I'm still dithering over filtration, and would appreciate some input

Possibly relevant factors:
- tank to be divided into 3 sections with craft mesh/plastic canvas
- sections will be moderately to heavily planted
- probably will be adding 1 nerite snail and possibly 1-2 Amano shrimp per section

I've got 3 potential filtering schemes in mind:

Sponge filters x3
Pros:
- easily driven off of 1 air pump and a gang valve
- less turbulence for bettas, but still good surface agitation
Cons:
- less helpful in actually keeping the tank clean

Tiny HOBs x3 (Azoo Palm)
Pros:
- offers more mechanical filtration and potential chemical filtration if/when needed
- adjustable flow
Cons:
- that's a lot of things to plug in...

Canister with spray bar
Pros:
- can attach inline heater, IMO the easiest way to keep a constant temp
- overkill mechanical & bio filtration
- takes up less swim space in the tank, theoretically (see Cons)
- I already have one
Cons:
- will possibly require some tinkering to get the spray bar in place with the dividers, or a compartment across the rear of the tank. (Or position the spray bar sideways and create a flow longways across the tank? I'd be concerned about the flow strength, but maybe...)

For the first two options, I'm also wondering if I should stick with 1 heater (in the central compartment) or 2 (left and right) to make sure the whole tank is evenly heated.

Advice (and any factors I didn't think about) appreciated, thanks!

 

Regarding heaters:
Two is one and one is none.

I always run two heaters, because when one fails you lose your fish, and it can happen overnight without warning.

Tank temperatures change quickly under cool night circumstances and you might not notice until it's too late.

I can't imagine it would be too difficult to fabricate a suitable spray bar, or just cut and extend yours using some vinyl tubing. Epoxy putty will take care of any odd fittings that don't meet up.

 

I recently purchased a 20 long for 2 of my Betta's. I am having my kitchen remodeled so I haven't set it up yet. I am going to get my contractor to make an acrylic aquarium divider like the one in the photo below. The one in the picture can be purchased from the UK! Here is the website Aquarium Dividers I don't know how to convert from our inches to the metric system, much less from pounds to dollars etc. I found out how to make one on youtube,
I am not going to put some divider that needs suction cups, they won't stay stuck on the tank with stress coat or whatever you use in the water. The 2 acrylic pieces that hold the divider made in the UK picture, that would be under the gravel or the sand could be the length of your tank, with several slots. You could choose to make a section larger or smaller or take one divider out or add a divider. I think the UK divider is so smart and so gorgeous!

 

Personally I would put about 10 times that many holes in it

 

I would suggest using Poret foam as dividers (Poret foam is a high-end sponge), with power head on one side sucking water in and pushing out into other side of tank. You will have internal filtration this way, no need for HOB etc, and the Poret foam will be your filter . You also get smoother, softer flow across your tank. Practically no maintenance on the tank. (I use Poret foam in my mattenfilter sump set up, I haven't cleaned the foam in 18 months. I probably should at this point but it's been 18 months!! So yes, low maintenance) Some food for thought.

I have tried using PennPlax aquarium dividers in the past but ran into filtration issues... Basically needed a filter in each compartment because of poor circulation.

 

I'd done a little reading on that -- sort of a mattenfilter-as-divider (with the bonus that that divider would definitely prevent the bettas from seeing eachother XD). The width of the foam might be a slight downside, but if it's removing other filter objects from the tanks, that probably evens out I'll look into it a bit more, thanks!

 

It's not the "prettiest" but it's extremely practical. Not sure how wide the baffles need to be. Mine are 3 inch baffles which is very wide (only first inch or so actually has aerobic bacteria, but the additional width gives more structural support and the foam blocks gets filled with gunk. Two inch wide blocks should work fine, one inch wide blocks may be pushing it, but may be ok too.