Making A DIY C02 Unit and C02 Mixture Article

Big Vine

Elite Fish
Feb 7, 2006
3,895
9
0
47
Florida
So basically I can use a much smaller bottle as a bubble-counter, if I want to...gotcha. (I probably won't)

Changing 1 of the 2 bottle mixtures every weekend (i.e. staggering) is a good thing, but you're saying it would still be better to have both of them up and running throughout the 1st week?

Hmm...would starting with just 1 bottle for a week and then adding a 2nd (at which point things will remain consistent) be all that bad?

I'm guessing things will work out fine either way, but just thought I'd pry on the subject a little bit more. :rolleyes:

Thanks again for your guidance.
I've read so many 'horror' stories with DIY CO2 'gone wrong' and total fish losses with subsequent entire tank breakdowns, etc., that I wanna make sure I get every little detail right from the get-go...regardless of how trivial or paranoid some of my concerns might seem. ;)

BV
 

depthC

Superstar Fish
Feb 24, 2003
1,417
0
0
WI
Your right whatever way you want to start up the bottles go for it, wont differientiate much if any thing.

And your right, best to know what your getting yourself into. I myself have gotten co2 mix in my tank. It was super cloudy, did a couple huge water changes no fish losses.

Andrew
 

Big Vine

Elite Fish
Feb 7, 2006
3,895
9
0
47
Florida
It's been 10 hours since hooking up my DIY CO2 mixture (2 cups sugar, 1/2 teaspoon 'Active Dry' baker's yeast, water up to start of curvy part of one of the 2 liter bottles), and there are no signs of CO2 in the tank.

I held my pinky under the water until it burned, then went down in temp. until it didn't burn---this is the water I put in the mixture bottle.

I even blew air through the tube (already fastened into the bottle cap) prior to hooking the cap up to the bottle, and I could hear the air churning in the HOB impeller, so I know the air is getting through.

Should I disconnect and shake the bottle again? Just wait longer?

BV
 

Big Vine

Elite Fish
Feb 7, 2006
3,895
9
0
47
Florida
Just once, GIS.
-2 cups sugar, 1/2 teaspoon of 'active dry' baker's yeast
-added water (just hot enough to not be painful on my pinky finger)
-shook vigorously to break up clump of sugar at bottom of bottle

Like I said, I even blew into the end of the tube that goes into the mixture bottle, and I could hear the churning of the filter as the impeller broke up the air bubbles.

There is no pressure whatsoever on the mixture bottle either, so nothing is happening.

Should I disconnect, shake the crap out of it, then reconnect first---or just skip all that and try mixing again, GIS? Anything I should do differently this time?

BV
 

Big Vine

Elite Fish
Feb 7, 2006
3,895
9
0
47
Florida
Okay, not long after my previous post here, I started hearing churning noises in the filter. They've increased in frequency...up to at least once per minute. I think it'll just take a bit of time for the pressure from the CO2 to become uniform throughout the ~4 ft. of airline tubing that it must travel through. At that point, it should start being a lot more consistent and frequent.

The good thing is that the intake tube on the HOB is clear enough to see the bubbles through, so I'm able to monitor things there quite nicely. I'll keep you posted.

Thanks.
BV
 

Big Vine

Elite Fish
Feb 7, 2006
3,895
9
0
47
Florida
pH drop and CO2 bubbling questions

My pH has dropped from 7.2 to 6.4 over the last two days, now that the CO2 is up and running.

Is this sort of a swing something to be concerned about?
(I'm guessing not; especially given the fish I've got in there)

Both bottles have 2 cups sugar.
The 1/2 tsp. yeast bottle is producing about 1 bubble per second. (took 2 days to get going like this) The 3/4 tsp. yeast bottle is producing several bubbles per second (this started within a day of hooking it up)

Sound about right?

BV
 

Strider

Small Fish
May 27, 2005
32
0
0
If there are nightmare stories of the sugar/yeast getting into the tank could one not add another empty bottle in series with the first?

The empty bottle would at first push out air, but as CO2 starts to fill it will eventually use the second bottle as a holding tank. THen if you either get back flow or yeast/sugar siphon it will all go into the second empty bottle sparing the fish tank.

Anyone try this?
 

Big Vine

Elite Fish
Feb 7, 2006
3,895
9
0
47
Florida
Yes, Strider, that's an idea that has been mentioned in this thread. Basically the 'holding container' is used as a bubble-counter (which, as you pointed out, is also an added safeguard against the mixture entering into your tank).

The 'horror stories' I've heard have been from LFS people who don't know what they're talking about. For example:

One guy told me how extremely important it is to have the CO2 mixture bottle(s) located above the level of the tank. His reasoning was that, if kept below the tank, the tankwater would initially (prior to the mixture giving off CO2) be 'sucked down' and into the mixture bottle. Then, once the CO2 really started being produced, the pressure would force the yeast mixture back up and into the tank (thereby making a huge mess and potentially killing everything in the tank).

Sounds like a horror story, BUT...
The guy also told me that he submerges his airline tubing into the water inside of the mixture bottle---which is a BAD idea!

As long as there is a gap between the end of the tubing and the water inside of the mixture bottle, then there's really nothing to worry about (especially if---as you should be---you are using a check-valve to prevent tankwater from flowing down into the mixture bottle).

BV
 

jamesw

Large Fish
Sep 15, 2006
203
0
0
Surrey, England
ok im a little worried made a Co2 unit and got it hooked up but i have to go out soon, how will i know that it wont explode are there any little things i can do to test it? also i only have a 2L bottle hooked up will this still work on my 180L tank?
 

Last edited:

Jayrod7

Large Fish
Dec 1, 2005
298
0
0
Omaha, Nebraska
Is there any way to turn it "off" after you have made the mixture?
From little i know about the co2 is that the yeast reacts and puts off co2. the gas builds up and goes through the tube into your filter/tank/airstone. I dont really think there is a way to stop it. If you just put a cap with out the tube in it then the pressure would most likely build up and explode, which wouldnt be a good idea, you can always just take the tube out and put co2 into your room. Its not huge amounts of co2 going into the room so you should be fine. In baking you usualy put more than that in so it wouldnt be a problem.

I am planning on building one or 2 of these this weekend. Im going to test it in maybe my 10 gallon. Do you put the bottle above your water or below, or does it even matter? My question is how you exactly defuse it, iv read every post on this thread so far (yea yea). What does hooking it up to your filter do? wouldnt it just suck up all the co2 and put out freshwater? then what about the airstones, do you just let the air stone sit in the water?
 

ishar

MFT Staff
Jul 27, 2007
1,490
0
36
36
Hamilton, ON.
hey, I am in the process of setting p a DIY CO2 bottle as described in this thread, but I am wondering if there are any sort of dangers to my fish with this? I know it changes the pH but I do not yet have a pH test kit, but is there anything I need to watch for?
 

ishar

MFT Staff
Jul 27, 2007
1,490
0
36
36
Hamilton, ON.
ok, well it is now set-up, but it isn't producing bubbles. I thought it'd be too cold so I put it into a bucket of hottish water to warm it up, but still no bubbles, and it has been an hour now. Should it be producing by now or is it just getting started type thing?
 

ishar

MFT Staff
Jul 27, 2007
1,490
0
36
36
Hamilton, ON.
well now it has been up for 4 hours and still no CO2. When I lightly squeeze the bottle it does not feel under pressure, and when I squeeze it a little bit more it will put air into the filter- meaning that no hoses are clogged. I resituated the hose now just to check and see if that will help, so hopefully that helps.