Filters for Betta tanks
Could I get some advise on filtration for my tanks? I'm here in Japan and while most equipment is available it is hard to get good information (language and communication problems) and information on the net is contradictory. I want to set up 4 tanks (900cm x 200 x 300cm (36" x 7.5" x 11.5") or 14.5 gallons each. Tanks will be set up in my study with two adjacent for a total of 1800cm or 71" (approx length) one row on top of another. I plan to divide each tank into separate compartments for my male HM Betta's. No other fish are involved. I currently have half a dozen 12 liter individual tanks each with its own filters (outside). It's a hassle to change all these filters...let alone all the wires, etc. Also, I like to shut the filters off at night for the comfort of the fish. I don't like the way Betta's are generally handled in those confined bowls and tanks. I like for there environment to me as natural as possible
What would you suggest to filter these tanks? I can set up a siphon between the two tanks to maintain levels if it is necessary and I'm pretty good and plumbing. I'm looking for ease of maintenance, aesthetics (this is my study) and the best removal of any odors. In-tank filters distract, and require to much handling, external...the same, but better. Over the tank filters...would that create to much turbulence? There's not adjust for flow. I thought a canister might be good, perhaps with a spray bar to distribute the clean water. Not sure if they are adjustable return to keep turbulence down. I could run the filters for a few hours per day, switching between the two sets of tanks.
I would appreciate any input and suggestions you may have.