20g high (betta) planted tank: canister filter; water circulation and water flow


So, I've been having trouble with my 20g high planted tank, specifically with my water quality. I suspect some of this may be related to water circulation and having too many "dead spots" in the tank. I'm currently running an AquaClear 70 HOB.

Important to note, this tank doesn't have a betta or any fish in it, as of yet. Just 3 mystery snails and 2 hardy cherry shrimps plus some pest ramshorn snails (the other shrimp and snails died.)

I plan to upgrade to a canister filter and have more bio filtration and better water circulation. My concern is water flow. I have water spangles that cover about 25-50% of the water surface, and I plan on getting a betta for the tank. All that being said....my questions:

  • Will the return spray bar have too much water flow for the spangles and the betta? Can that be reduced by increase the size of the holes or wrapping the spray bar with a sponge filter to diffuse the return?
  • If I diffuse the return on the spray bar does that ruin the overall circulation of the tank?
  • Would a lily pipe be a better option: either a violet pipe or a spinning pipe?
  • Should I use a Y-connector and split the intake and put one in each back corner to avoid any dead spots from the intake?
  • What would be the best positioning for the intake/return? (Currently I'm thinking on the same side, so I get a circular flow: intake current pulling across the bottom, while the outflow goes across the top in the opposite direction).

I know those are a lot of questions, but I'm trying to determine what's the best approach. I don't want to stress a fish with too much flow, but if I don't have proper circulation, I'll end up with water quality issues. At this point, the aquarium has been up and running for 6 months, and the plants are doing well. I do have what I call "gray snow" that collects in places that I siphon out regularly, and I'm hoping improved circulation will prevent this. My ideal goal is to have a mature planted tank but the Spring of next year and my WQ issues cleared up so that I may stock with more shrimp and a better.

Photo is current hardscape/plant placement for visualization.



Honestly for a 20g I do not think you need a canister filter. I would do just a regular HOB (I love the SeaChem Tidals, they are low profile, quiet, and easy to clean) or you could even do a sponge filter/box filter- great biological filtration and agitates the surface so it keeps the water moving around + cheap!
However, if you are stuck on a canister I suggest getting a Fluval, I just got one and love it! I also have floaters and what I do is just point the output nozzle towards the back wall and it diffuses it pretty well. Also the Fluval has a lever that lowers the output so that helps. The Fluvals do not come with a spray bar but you can always order one.
If your tank is properly cycled, as long as you have water movement, do steady WCs every week, and appropriate fish stocking-water quality will be just fine.
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