What is the optimal CO2 diffuser location for 46g bowfront tank?

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.


Aquarium Advice Apprentice
Jul 2, 2020
I have a current 46g bowfront tank that is about to be replaced (center brace snapped). I've got a Fluval 407 canister filter and a CO2 art diffuser. The current setup has the CO2 diffuser and outflow from the canister about 1 foot in from the side wall along the back, directing the CO2 from right to left. I also have a separate hose running to a small diffuser that sis in the right corner to feed some CO2 low on that right side because nothing was growing there. I tried my best to show what it looks like now - the blue are the two diffusers, the black box is the outflow from the canister filter the white circles are CO2 and the green arrow shows the direction of the water flow.

What is the BEST way to set up a CO2 circuit in a new tank? All the way in one corner pointing along the back wall? Directing the outflow towards the front of the tank so it follows the curve of the front wall and put the little one along the back in the other corner?CO2.png
You usually want the output from the filter directing water towards the front, so that water hits the front of the aquarium and gets directed downwards. And then have your diffuser at the front close to the substrate in the downward direction of flow so the CO2 gets distributed around the tank and doesnt just offgas at the surface.
I'm getting lily pipes (currently using the stock stuff and hate it). Do I have the pipes on the side of the tank in the front directed towards the other side, and the diffuser opposite it on the other side? And put the return in the back on the same side as the lily pipes? Like this:
New setup.png
Top Bottom