Question about DIY CO2 injection

Harlock

Harlock

Educated Idiot
Dec 15, 2004
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So, I'm going to make me one of these DIY injectors for my 29g FW out of the 2L pop bottle. I am running two Penguin 125 Bio-Wheel filters and know I am burning a lot of CO2 to atmosphere, so I want to make sure I get some in the tank. I know the longer the bubbles stay in the water column the better for CO2 absorption, or am I misinformed? If I am not misinformed, do you think using a second, smaller pop bottle (like a 20 oz) cut so I am only using the top 1/3 (think bell-shaped) hooked on the air line tubing but above the air stone to trap the CO2 bubbles would help more CO2 into the water column? Thanks for the input!
 
I would recommend making a diffusor using a gravel tube and powerhead.

You could use the pop bottle method, but it is much less effective (especially considering your HOB Penguin filters).

If you had a canister, I would say that may be fine.

I used one of those 'passive' diffusor methods...I wasn't pleased.

Thanks,
Steve
 
Before building anything, it won't hurt anything to perhaps try just using a simple extra fine airstone for a couple days to see where that gets you. (If you have soft water, you may find that you can't inject a whole bunch of co2 without your pH plummeting.) I get pretty good saturation with that method. But yes, a bell diffuser (what you are talking about with the soda bottle) is also a good method and a power reactor (what Steve is talking about) are probably the most efficient method - provided that you've built it efficiently and correctly.

By keeping your water level high, you will cut down on surface disturbance from your filters - this will help keep co2 levels higher.

I trust you've checked your kH/gH/pH out already to make sure your water can support co2 injection fully? And that you also know how to calcuate Co2 in ppm.
 
Yup. kH is 120 mg/L, gH is an outrageous 420 mg/L (and yeah, I checked this twice), and pH is 7.6
So, lemme see...
CO2 = 5.056 mg/L. That's pretty low. I still have some fish to add yet... will that make that much difference?
 
Well that's before you started adding co2...right? The fish won't make a big difference at all. The co2 range you'll want is about 22-25 ppm...next thing to do is get her up and running, I think.
 
Leopardess said:
Well that's before you started adding co2...right? The fish won't make a big difference at all. The co2 range you'll want is about 22-25 ppm...next thing to do is get her up and running, I think.
Click to expand...

Heh, yes, no CO2 injection as of yet, only the stuff to make it. Picked up some silicone airline tubing, a check valve and airstone today. Also drilled the pop top. Adding the bell diffuser will be simple, so I'll check it with a simple airstone first. I suppose the nice thing about a 29g is that they are high, so there will be more time for the CO2 to diffuse. My plants aren't that demanding, but I know they need more CO2 than they're getting. Plus, I love the way the plants look, so I want them to grow in nice and I'll fill in gaps later.
 
I'm using DIY CO2 injection in an 80 gallon heavily planted tank. The plants were doing pretty well without the benefits of CO2 injection, but I thought I'd give it a go to see there are any improvements to be had.

do you think using a second, smaller pop bottle (like a 20 oz) cut so I am only using the top 1/3 (think bell-shaped) hooked on the air line tubing but above the air stone to trap the CO2 bubbles would help more CO2 into the water column?
Click to expand...

I'm using this method right now. I'm using the top 1/3 of a small pop bottle as a bell trapping the CO2 bubbles. The airstone is weighted down to prevent the bell from floating to the top from the big CO2 bubble trapped in the bell. The CO2 bubble doesn't go anywhere, and it'is in constant contact with the water so I am hopeful there is a high rate of CO2 absorption into the water column. This method seems to be working well as I didn't really want to inject CO2 into my canister filter, and I'm not running a powerhead.
 
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I am using a bubble wall type diffuser, and I usually see about 15 ppm CO2, It is the Hagen one(I think) with 2 2L bottles attached to it. My filter is a Whisper HOB, and the water line is above the output, so very little surface turbulance.

Yup. kH is 120 mg/L, gH is an outrageous 420 mg/L (and yeah, I checked this twice), and pH is 7.6
Click to expand...

Is that right out of the tap, or aged water? Seems like alot of CO2, naturally occuring, especially with 2 bio wheels!

The co2 range you'll want is about 22-25 ppm...
Click to expand...

That is the high range, like max. Any more than that, and you start to put your fish at risk(your PH would also be ~7.0-6.8). I wouldn't go that high. If you see that with DIY, and with the bio wheels, don't let anybody know how you did it, and patent it. You'll make a fortune.;) I am going to guess that doing CO2 with the bio-wheels is not going to do much. The bio-wheels will gas off allmost all of it, as fast as the filter can pull it in. If you want to keep the bio-wheels, I would suggest going with some very easy plants that don't High light levels, and therefore, won't need CO2
 
It can be done, it just takes a little extra :D
I've got a 10g with a Penguin 170, and thought there was no way I'd get any significant CO2 in the tank. It takes 2 2L bottles, but with the airline fed directly into the filter's uptake, the CO2 generally stays around 10-15ppm which seems enough to keep the Crypts happy :)
 
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