[MissCris]

I decided to get my feet wet on pressurized CO2 with a fluval mini CO2 set to try on my 20g (it's the 45g size). The kit seems to come with the tank, gauge, tubing and diffuser.

I will be buying a drop checker before installing it on the tank, but I've heard varying information indicating that you should use a different concentration of reagent with very hard water. My water is super hard; do I need a different reagent or do I dilute it somehow?

What else do I need?

Also, can I run the CO2 for only a few hours each day and still get good results, or is it best to run it for the majority of the photo period, turning it off just a couple hours before lights-out to disperse the gas.

I know from cruising the forum over the years that a full size setup is cheaper in the long run, but I wanted to try a low-investment version before I drop $200 to see if I actually want to commit to the maintenance of a true high-tech setup.

 

[Scully]

I just want to start off by saying, as someone who uses a cartidge based CO2 system, it's a lot more maitnence than a traditional system. Especially with the fluval system. There's no way to put a solenoid on it to automatically turn it on/off, so every day you'll have to turn it on, check the BPS, and turn it off. You'll also have to change the cartidges more often than you would a CO2 tank. I use small cartidges and made a tool out of a socket and tape that lets me change them quickly with a drill for minimum CO2 loss. I have to do this once a week or so, depending on how many BPS I run. It will probably be around 3 weeks on the 45g cartridges(I use 16g).

Don't let that discourage you though, it's definitely nice to not jump right in on a full high tech system. You can use this experiment to see what else you might need to change if you fully commit to high tech.

As for the solution question, I don't know. I don't use a drop checker, I just experimented with different BPS until I got my PH to drop 1 point over the course of a day (NOTE: this was without any livestock in the tank). Hard water might affect how this method would work.

As for how to run the system, I'd say keep it going from either one hour before lights on until an hour before lights out. This will allow CO2 to build up for the photoperiod so plants can start using it right away, and then let them use up most of it before the lights go out for the night. Start with 0.5-1 BPS and see where that gets you with the drop checker, or whatever method you use. Then you can go from there to get to a comfortable spot.

 

[Kubla]

One of the most important things with CO2 is consistency. You want a steady level through your photo period, so as Datsun said, having it come on an hour before your lights usually works out pretty well. I think most here shut it off about an hour before lights off. The level will stay pretty steady for that amount of time and will save you some CO2. Some run the CO2 24/7 but I don't think you'd want to do that with a Fluval mini on 20g.
Are you upping your light levels when you add CO2? CO2 on it's own should lead to less maintenance (other than the maintenance of the CO2 equipment). You probably won't see a large increase in growth unless you increase the light level. Plant nutrients are the fuel for growth, light is the accelerator.

 

[MissCris]

One of the most important things with CO2 is consistency. You want a steady level through your photo period, so as Datsun said, having it come on an hour before your lights usually works out pretty well. I think most here shut it off about an hour before lights off. The level will stay pretty steady for that amount of time and will save you some CO2. Some run the CO2 24/7 but I don't think you'd want to do that with a Fluval mini on 20g.
Are you upping your light levels when you add CO2? CO2 on it's own should lead to less maintenance (other than the maintenance of the CO2 equipment). You probably won't see a large increase in growth unless you increase the light level. Plant nutrients are the fuel for growth, light is the accelerator.

I actually just upgraded the tank to high-light (Beamswork FSPEC), and realized that between my light and fertilizer regimen that I was probably going to have to switch from using Excel to using gas if I didn't want a sea of algae. Plus it would let me finally grow some of the more demanding plants that I've been wanting for years.

 

[moke]

get a pH pen/monitor instead of the drop checker, which gives you an estimate of co2 concentration what it was 2-3 hours prior. pH gives immediate, real-time estimation. this will make it easier to dial in your injection rate. as was mentioned, try to achieve a 1+pt drop in pH by the time the lights come on. takes me about 3 hours to drop ~1.25 pts. increasing surface agitation prevents co2 from reaching lethal levels. off gassing of co2 is vital in dialing in your co2 injection. i use a surface skimmer and i have 2 lily pipes pushing a combined 300+gph in my 20h.