Hello, co2 setup question


Junior Poster
Apr 24, 2009
Central Vermont - USA
So my current tank is a 75g standard tank with a coralife 4x65w power compact setup. The bulbs are a 6700k/10000k mix. Filstar XP3 canister filter with a smartheater attached to it. It houses three Discus, otos, Amano shrimp, cherry shrimp and soon some sterbai cories. I have pool filter white sand to bring out the colors of my discus as I felt they were too dark with the flourite I was using.
My tank grew great with flourite but its too sharp for the cories barbels.

I have a mixture of high to low light plants but would like a tank of mostly HC and HM. I would love to have those two alone but they dont seem to do to well with the sand and no co2 right now. I use the ei dosing method and have had a successful tank without co2, I just want to do some carpet plants as well.

I am looking to build or buy a co2 setup and would like some recommendations from the expert here!!
I was planning on using the spray bar from my xp3 canister filter to diffuse the co2, to save some initial setup costs of course. I would prefer to have a ph controller.



Junior Poster
Jan 21, 2009
Hi David,

I'm no expert but here is what I did. I bought a new 5 lb CO2 tank with valve off ebay. The guy I bought it from has one for sale here NEW 5 lb CO2 Aluminum Cylinder W/Valve co 2 tank 5lb - eBay (item 140316096321 end time Apr-27-09 08:46:20 PDT). Your tank is three times the size of mine so you may want to go with a larger tank.

I bought an Aquatek regulator also off ebay. No special reason behind that brand. It is just what I decided to try. Rex Grigg sells regulators but I have only bought fertilizer from him. I do have a 58 gal that I will probably add CO2. When I do I will probably call Rex and talk to him about a regulator with multiple needle valves so that I can inject the CO2 in a couple of places. In the three months I have had CO2 I am learning that being able to get good distribution is very important. Hopefully those with more experience will comment on whether or not multiple injection points is a good idea on larger tanks.

I had the tank filled at a fire extinguisher shop. Cost me $10. The tank will be filled by weight and the pressure will be around 800lbs. I recommend you have a way to secure the tank while transporting it to avoid damaging the valve. I put mine in a cardboard box and wedged it behind my seat. I wouldn't leave it in an enclosed parked car. Unlikely but the raised temperature could raise the pressure until the pressure relief valve actuates.

I use a reactor after my filter to inject the CO2. I saw one on ebay for $10 so I bought it. Saved me the trouble of assembling it myself. There are plans on this site and others. A google search should find them for you.

I thought about but passed on a PH controller. Instead I went with a solenoid on the regulator and have it set to come on and go off with my lights.




Lifetime Charter Member
Lifetime Member
Jan 15, 2009
Find the best regulator and solenoid setup you can reasonably afford. Skip the Milwaukee regulator combo. You'll constantly fiddle with it. The instructions for swapping tanks on it are rather involved as well. If you can swing it, Sumo Regulators makes a really nice rig and I've heard the Rex Grigg units are very nice too.

There are several sources for tanks. In most cases, for a 5lb tank you're probably going to be paying 50-80$ for it depending on if it's filled or not, at least anywhere near the Boston MA area unless you get really lucky.

Generally speaking people on this forum pan the pH control of CO2. Plants won't use CO2 without light, so a simple timer will suffice to control the solenoid. I use the same timer my lights are on, some people use a second timer to ramp up the CO2 in the tank a bit before the lights come on and shut off the CO2 a bit before the lights go out.

Another use for the pH controller is to prevent the end of tank dump of CO2 some cheaper regulators are prone to. They'll plug the controllers output into a time and set the pH a touch lower than they'd ever really want the tank to be. As long as the timer is on the CO2 will flow, but if for some reason the regulator dumps too much CO2, the pH controller will catch it and shut off the solenoid. Unless you need that peace of mind, or like gadgets, you're likely to be better off with a better regulator in the first place which won't dump CO2 when it runs out and comes with a better needle valve.

I didn't find the Flourite too sharp for the cories, but they also make a sand product as well so that may be an option. I've used both types in my tanks and haven't really seen any issues.

I'm curious on the lighter sand bringing out the colors of the discus as I usually find most fish have better colors over the darker substrates. I've never kept discus though.