| | Dupla S CO2 Reactor question
Hello, all! I'm a new member of this list, and would very much appreciate help with a question I have about a Dupla S CO2 reactor.
I've recently upgraded the lighting on my (planted) 50g, and now am almost ready to add CO2. I've acquired a regulator, needle valve, check valve, bubbler, and (this last week) a Dupla S reactor. I have a question regarding the connections on the Dupla.
I had assumed (from reading about it on-line) that the CO2 is simply diffused into the water passing through the reactor (I was planning to put it in-line on the discharge side of my canister filter/pump), and carried into the tank. However, the instructions say that you "select" the CO2 diffusion rate by running a hose from one of three (3mm) take-off points on the side of the reactor, and direct that flow into the tank.
Why would I need to do that? I thought that the idea was that the CO2 (input via a 3mm end connection on this reactor) would diffuse into the water as it flows between the (9mm) inlet and outlet connections.
Now I'm wondering if I've assumed incorrectly about how the reactor works. The instructions do mention that Dupla recommends that it be "installed on a separate pump circuit." Perhaps I'm meant to get a much lower flow ancillary pump, and so have a small flow of water pass through a CO2 gas area (i.e., large bubble) at the top of the reactor. However, even if this possibility is correct, I'm still puzzled by why I'd direct a CO2 takeoff into the tank. If I wanted to limit the size of the CO2 "bubble" at the top of the reactor, wouldn't I slow down the CO2 supply (via a needle valve adjustment and observation of the bubbler)? Wouldn't directing CO2 into the tank from a "selector" 3mm port *still* be adding more CO2 to the tank?
I would appreciate very much any enlightenment offered!
Thanks and Cheerio,