How-To on DIY CO2 Injection

Cichlid Woman · Dec 14, 2002

Hi, folks,

My pH is running from 7.5 to 7.8, and I want to lower it to breed Rams and maybe other things. And my plants aren't doing so well, either. So ... DIY CO2! I tried to search the site for it, but was unsuccessful. The terms "DIY" and CO2" are both too short to run a search, and "dioxide" resulted in only a few posts, none of which addressed the how-to's of CO2 injection. So here goes ... new post.

My 38-gal planted tank gets 40 watts of sunlight-spectrum fluorescent light, and I can't (yet) afford compact fluorescents. I consulted a KH/pH chart that determines CO2 levels in the water, and mine is low. So, for now, trying DIY CO2 seems to be the answer. From what I've been able to find out, here is the procedure:

1) Drill a hole in the cap of a 2-liter pop bottle

2) Run some airline tubing through it and seal, with aquarium acrylic (which I don't have) or a hot-glue gun (which I do have)

3) Half-fill the bottle with warm water and add a package of yeast and a cup of sugar. Wait 24 hours, until it starts to bubble.

4) Connect the other end of the airline tubing to my tank. (And here's where it gets crazy--how to diffuse the CO2 bubbles into the tank appears to be limited only by the aquarist's imagination ... ) I figured I'd dig out that 18" bubble wand I've got somewhere and connect it to the yeast bottle, then put it in the center back of my tank next to the substrate. Small bubbles will dispurse the CO2 bubbles before they leave the tank, right?

Concerns and questions:

1) Do I have the procedure right?

2) Will this stuff kill my fish if I do it wrong? (How do I measure the CO2 going into the tank, and do I need to?!)

3) WILL THIS THING EXPLODE ALL OVER MY LIVING ROOM AND MY CHRISTMAS TREE?!

I'm waiting until I hear from more experienced minds than my own before I try this.

Eagerly awaiting your advice, info, and thoughts. Thanks,

-- Pat

firetank · Dec 14, 2002

hey,

im using diy too.....(watch the plants GROW!!)

as far as i know just make sure you dont knock\tip over the bottle, and you wont have any probs...ihe pressure doesnt build up enuff..

the rest sounds familiar...

i tihkn i read about putting the co2 outlet into a filter intake to distribute it better......

http://www.tropicalfishcentre.co.uk/Diyco2.htm

try here..

Cichlid Woman · Dec 14, 2002

Thanks for the link! I printed it out. It uses more sugar than other recipes I've seen, but gives good reasons for doing so.

What about the "bubble wand" to disburse the CO2? Sound okay?

-- Pat

firetank · Dec 14, 2002

sounds ok..youre after getting the bubbles as small as poss i think, more surface area to distribute.......

wannabesan · Dec 14, 2002

Fail Safe

If your worried about injection(the bad kind) into your tank then try this:

Use a second 2-liter or 3 liter bottle( if you really want to be safe)

drill 2 holes in the cap

Insert tube A from your DIY bottle into the second bottle, run the tube all the way to the bottom of the bottle.

Insert but B only an inch or two, this tube will run to your tank.

Seal both tubes.

This setup will provide a spill over resevoir incase too much pressure forces the CO2 swill out of the first bottle.

Richer · Dec 14, 2002

DIY works well for tanks 20-30 gallons and lower... for larger tanks, it gets more tedious to keep up with this method. For a 38 gallon, I'd suggest using two bottles instead of one. The airstone method of diffusion might work, but I'd suggest some sort of power reactor to really get results. What kind of filter do you have? You could probably inject the CO2 through there to get better diffusion than through an airstone... you could also try injecting the CO2 through a powerhead as well.
The DIY mixture found here is what I used to use when I did DIY injection.
Seems like you are already familiar with the pH/kh table for determining your CO2 concentrations. Just keep on using that to figure out if your CO2 levels are good. You want to keep the levels at around 15-20 ppm. I don't believe CO2 begins to annoy fish until it goes above 30-35ppm.
As for the risk of a bottle exploding. What I did was I went to the local department store (in this case Zellers) and found myself a flip top plastic trash can. I made a notch to allow my CO2 line to go out of the trash can, and just stuck the bottle in there. Not only would it contain any kind of explosion, the trash can looked half decent sitting there on the ground, plus it was water proof... thus I partially filled with water and stuck a heater in there... allowing me to keep a constant temperature for the yeast bottle and allowing the yeast to produce CO2 more consistantly. I might have pictures laying around here somewhere if you want to see what I'm talking about.

If you like the results you see from your DIY CO2 injection, you will love the pressurized method even more! Its much easier to inject CO2 via pressurized... once you get the right about of CO2 going into your tank, you'll never have to touch the valves nor the cylinder for months on end.

HTH
-Richer

djlen · Dec 14, 2002

Be very careful how much CO2 you run into that tank initially. I have a 40 gallon tank and I run the CO2 line into and airstone which is in the uptake tube of my Aqua Clear filter. It does a good enough job to keep my PPM/CO2 at 15/20.
HOWEVER.....when I tried using my power head (with the same method as above) it was sooooo efficient that my PH dropped into a dangerous, IMO, area. So I went back to the AC filter and I like the results.
MY point being.....whatever you do, start slowly and keep an eye on your water conditions. Especially if your KH is low. You really have to experiment around until you get the conditions you want and feel comfortable with.
Len

Cichlid Woman · Dec 14, 2002

I'm using an Aqua Clear 200, and feeding the CO2 directly into the uptake tube sounds good ... but how do you do that?! The uptake tube is fully enclosed, isn't it, except for the slots at the bottom where it sucks the water in?

The double-bottle setup to avoid overspills sounds good, too. Do I still need that, though, if I'm using a check valve in the tubing? Your method eliminates the possibility of an explosion due to pressure, though, and a check valve doesn't. Maybe I should just forget the check valve and use the second bottle ...

This set-up is going to be sitting in my small living room, and I don't have room for a trash can behind the tank, Richer. I sure like your setup, though, especially with the heater going and everything. I'd have to find something small, though, to fit in the space I've got.

Pressurized would be loverly, but $$ is an issue right now ...

Firetank and Richer both took me to the same link for the recipe, so that's the one I'm going to use (2 cups sugar, etc.)!

Oh, and my KH is 8. Should be enough buffering to handle the new CO2 without a pH crash, right?

Thanks BUNCHES,

-- Pat

irishspy · Dec 14, 2002

Originally posted by Cichlid Woman
My 38-gal planted tank gets 40 watts of sunlight-spectrum fluorescent light, and I can't (yet) afford compact fluorescents.

Hi Pat,

The others have good suggestions about CO2, but I also wanted to suggest adding more lights to your tank. You have a smidge more than 1 watt per gallon, and few plants do well at that level. (Mostly anubias, java fern, and a few others) If compact fluorescent is too expensive right now, you could still add another with hook-ups for two 20 watt bulbs. I did that one time and it wasn't too expensive at all. (Plus, you could set them on timers one-half hour apart, to give the fish a twilight effect, which is more natural for them) Combined with you CO2, this should turn your tank into a jungle.

--Anthony

Richer · Dec 14, 2002

A kh of 8 is fine for CO2 injection... it'd be pretty hard to crash that... my tank's kh ranges from 7-9 (I even got a reading of 11 once), and I manage to get my pH down to about 7 via CO2 injection. My plants love it =)

In response to irishspy's post, yes, lighting is an important component to plant growth no doubt about it. However, get your CO2 going first before you think about getting more than 2 wpg (watts per gallon) of lighting. Make sure you are able to keep your CO2 levels at 15-20 ppm at all times for an extended amount of time (a week or two). Once you are sure you can do that, go and get more light on that tank if you want to =). Once you get into that area, watching your nutrients closely is a must. More info on that later if you want it =)

HTH
-Richer


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How-To on DIY CO2 Injection

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