Originally Posted by Aquaticfan
Wouldnt recommend it for a hob? Your reasons? How is a hob impeller and motor any different then a canisters? How about addressing the issues I've mentioned above? How much bubble rate are you running into your canister?
Sorry but this is a thread about reactors. Not canisters.I would be glad if you like to list a lot of other reasons to use a reactor over a canister if you like but really its not on par with the thread or what the op is after.
Injecting CO2 into an HOB is very different from injecting into a canister. When you inject CO2 into an HOB, the CO2 gets broken up by the impeller and some if it gets dissolved into the water column.
A canister, in contrast, works like a reactor. The CO2 flows down then intake and most work its way through the filter media before coming in contact with the impeller. In general, all the CO2 dissolves before this happens (the path in the Rena Filster XP is exactly the same as the previously shown reactor picture).
A canister will give you 100% diffusion with no micro bubbles. An HOB probably won't work any better than bubbling the CO2 into a powerhead (although you will avoid bubbles with the HOB).
I addressed most of your issues. However, these may have been missed.
CO2 in bio-media -- this is not an issue (I haven't seen a single documented case of it being a problem). The CO2 doesn't displace the oxygen in the canister (if it does, where did the O2 go
Control of CO2 diffusion -- the canister filter will give you 100% diffusion and allow you to evenly return the CO2 to your tank.
Amount of CO2 needed -- for 100% diffusion, a single canister should be able to handle this. However, many larger tanks have 2 canisters, which can both be injected.
I asked about using a canister because I was curious why someone makes the choice to build a reactor when a canister works the same way with CO2 introduced into its input.