DIY CO2: canister filter outflow injection reactor

[ukedude]

This is one of a couple of questions for which I have not found answers here (quite remarkable, really).

In my study of DIY CO2 generation and injection, I have not yet seen a posting by someone who has used a DIY source in combination with an inline reactor on the outflow line from a canister filter.

I have seen a great picture of an XP2 with in-line heater and in-line reactor, but the author admitted that he had not yet hooked up CO2.

My question is: does a DIY CO2 generator produce enough pressure to be used on the output line of a canister filter?

Obviously should something go wrong on the CO2 supply and the pressure drop, there would have to be a check valve to prevent sending water to the CO2 generator.

[Purrbox]

Generally most people seem to use the Inline CO2 Reactor on the Input side of a Canister Filter. Apparently this is less problematic for some reason. I have read of instances where people have used the Inline CO2 Reactor output of a Canister Filter, but this is less common and they often end up switching it to the input side instead. As to whether or not a DIY CO2 generator can build up enough pressure to be used this way, it would probably depend on the total volume of generation bottles being used and the mix that is being used. You could always give it a try, and it if doesn't work switch it to the other side. I would definately recommend putting a check valve before each of the generation bottle so that you don't have to wait as long for the system to build up pressure each time that you switch out one of the bottles.

[mr funktastic]

i think the biggest reason u have not seena post on it yet is becasue most people dont use a canister on anything less than around 40 gal(justa guess) and once u get up into those sizes DIY co2 becomes kind of innefective. so most people useing a canister will also be using pressurized co2.

[ukedude]

Excellent answers--many thanks! Here is a bit of follow up.

My reasons for preferring the output side are found in all the discussions on wear and tear on the impeller from introducing gasses on the input side, and the increased amount of impurities in the water before filtration. Putting the reactor on the output side avoids both of these problems, but may introduce others.

As for the canister, I am setting up a 29-gal after a move. Aesthetic considerations are important, so putting all the equipment (filter, heater, and now CO2) under the tank is one of my goals.

[Zezmo]

Once apon a time, my 55 gallon had DIY, CO2. It used a bubble ladder and a diffusion bell, and had a HOB filter. I would get 15-20 ppm or so.
I was concerned over "losing" CO2 to my HOB filter, and switched to 2x Fluval 303 cannister filters. This helped some, but my PPM's did not go up too much. I deciced the real problem must be I needed a more efficient reactor. So i build one out of an old gravel vac, and put it on the outflow (i used a powerhead before i switched it to the outflow). It had a venturi loop too.
This is where I learned one major reason folks do not do this much (or for long). You have no control over the "flow rate" on DIY CO2. If you add a highly efficient reactor, you can easily get too much CO2.

here is an old post where I just set it up, and was getting 45ppm (with a powerhead)
http://www.aquariumadvice.com/viewto...hlight=#472286

Here is 2 month later, when I got real good at DIY CO2, peaked at 130+ppm of CO2 and wiped out half my tank. I quickly went to pressurized. I lost enough $$$ in fish to justify the pressurized cost. Which turned out to be more reasonable than expected. ($40 2 dial welding regulator, $70 5lb cannister, and about $7 for the needle valve) (I filled the 5lb last month - so it lasted about 7 months, and was $7 to refill)
http://www.aquariumadvice.com/viewto...hlight=#521294

So bottom line, it can be done, it works well...maybe too well. And in the end, the lack of control on DIY CO2 makes it dangerous, once you get it working well.

[src]

I am probably the person with the setup you saw pictures of who had not yet added CO2. Well, I added it this week, and it works GREAT. I've had no issues getting the CO2 into the system, and am only running the output stage of the regulator at 6 psi, about 1 bubble/second at the moment. I'm using the AquariumPlants.com regulator, which produces larger bubbles than normal (2x, according to them).

[ukedude]

Zezmo, I just posted a question on this very topic, while you were typing apparently.

I would like to know if you looked at any in-line flow control valves before switching to the pressurized system and the welding regulator.

Perhaps you can reply on the other topic (http://www.aquariumadvice.com/viewtopic.php?t=84091) to keep the discussion there.

src, yes, I am sure it is your great picture that inspired me to ask this question in the first place. Your setup is very much what I had in mind (or perhaps, more correctly, your set up is what put the idea in my head in the first place).

I assume you are using bottled CO2?