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DIY CO2 questions

9K views 59 replies 19 participants last post by  ADJAquariums 
#1 ·
Alright so... I need a little help, ive got airline tubing, check vaulve and bottles to house the yeast and such, the only question is how much of water and yeast do i need for my tank, it is a 40 gallon and im going to use an airstone as my diffuser, any help would be much apperciated, thanks.
 
#3 · (Edited)
1/2 cup sugar and 1 teaspoon of yeast for every quart of water. Same as Koolaid! You should be fine with an Ocean spray 3 liter container filled 80% with the water.

What works best for me is to add the sugar to the room temp water in the bottle and shake it till dissolved. gently sprinkle the yeast on top of the water and let it hydrate for 5 minutes. It will begin falling to the bottom and appear to foam on the surface. Then gently rotate the bottle so the yeast mixes with the water.
 
#4 ·
DIY CO2 bottles produce a limited amount of CO2, so it really pays off to use a good method for diffusing it into the water. Otherwise, you will usually be very short on CO2. One efficient diffusing method is as described here: http://www.plantedtank.net/forums/showpost.php?p=1886010&postcount=2

I use 2 cups sugar, 1/2 tsp yeast, 1/2 tsp baking soda, in 2 liters of water. I dump in the yeast, the soda, then the sugar. Fill the bottle up just past where it necks down. Then I invert it with my thumb over the opening and shake it vigorously. Then, carry it over to the tank and connect it to the system. I use two 2L bottles, changing the solution in one every week. This is for a 65 gallon tank, and it gives me very noticeable improvement.
 
#16 ·
Its not exactly pretty but for free it works. I kept mine whole so I could use it as a bubble counter as well as diffuser. The syringe is available at any pharmacy I would think. Mine is a 10 ml version made for administering meds orally to babies. Good thing about these is no needle to deal with.
 
#22 ·
The short answer is..."it depends"

If you have an extremely heavy plant load, the amount of CO2 they make at night could push it over the limit for fish (depends on their sensitivity, etc).

However, this problem is more common with pressurized CO2 and not DIY CO2. You did not mention how many bottles of DIY CO2 you are running, but it is doubtful that it will generate enough CO2 at night.

If you are concerned, you could put an air pump with airstone on a timer so that it comes on at night, but again, unless you are running a large number of bottles on your 75 gallon aquarium, you should be fine.
 
#23 ·
Hmm it doesnt appear like my Co2 bottles are producing any CO2 unless i shake it rigourously for like 10 minutes and then its only like 5 minutes its going, im using 1/2 tsp of yeast and Baking soda, 2 cups of sugar, 2L of warm water and waiting an hour for the yeast to acctivate, anyuthing wrong here or is it my flaw? might try shortining the tubing from generator to my second bottle where the CO2 gets seperated from any bad "stuff that comes with it
 
#26 ·
I use boiling water in bottle first then add sugar let this cool to warm...in meantime I mix a tsp of yeast with a cup of warm water and a pinch of sugar. When bottle is just warm add the mix, cap and shake a bit then hook it in. Starts producing in an hour or two depending how much water is in line that it has to force back into tank
 
#27 ·
Usually when you see no CO2 production you have a CO2 leak, which could be at the bottle cap, or anywhere beyond that up to the bubble counter. The seal where the tube enters the bottle cap isn't good for much pressure, so a sticking or backwards check valve makes it leak there, or a sintered glass diffuser may take too much pressure to get gas flow through it, causing a back pressure and leak.
 
#28 ·
I think I may have this problem... I am using 3 two liter bottles with airline tubing pulled though the cap and sealed with silicone. I am getting a few bubbles through my counter (maybe 5 or 6 per min), but not as many as I would expect given 3 fresh bottles. Plus, if I shake the bottles I catch a whiff of fermentation (that putrid/overly sweet scent). Does anyone know a better way to seal 2 liter bottles? Would epoxy be a stronger seal?

And a totally unrelated question...
I have a 29 gallon moderately planted aquarium (same one as above) on which I am trying a DIY CO2 with a glass & ceramic diffuser. However, I use hang on back filters. I've read that the surface turbulence from these filters dissipates the CO2 from a DIY system so rapidly I may be wasting my time. Does anyone have a success story with HOB filters and DIY CO2?

Thanks
 
#31 ·
The picture works fine;

I would go over and check all the connections with some soapy water (drip the soapy water over the connections). If there are any bubbles that you can see forming, then you will know there is a leak.
 
#32 ·
Yea sounds like you have a leak. The best way I've found to seal the caps is to drill a small hole, get some rigid plastic tubing that the airline will fit over (either rigid tubing, or you could mutilate a barbed 3 way). Put the fitting in the hole, and surround it with hot glue on both the inside and outside of the cap. You can even pull it through the hole a bit to draw in the glue. Just don't get too crazy on the inside of the cap or it wont thread down. Also make sure your using an intermediate bottle in line(full of water) to scrub the air, otherwise you'll get some funky stuff growing in your tank... I like running a mininmum of 2 bottles, and I like the ~1 gallon juice jugs (the kind with the built in handle).

As for diffusion, one idea I've used before: a collection bell. doesn't have to be fancy, it can be difficult to keep it from flipping over when full of gas, the surface area exposed to the water is more important than the volume and if you can get some current past it you'll get great diffusion. Right now I'm using a chopstick diffuser(free) with a collection bell collar threaded on to the CO2 airline- made out of a clear plastic lid about 1" in diameter. It's got my drop checker in the green zone, in a tank with poor flow on the opposite corner of a 20L.
 
#35 ·
Are you going to use a separator bottle? (one that has the lining from the 2 liter bottles connected to it, and this separator bottle connects to the actual tank)

I'm still trying to figure the exact specifics out, but it looks like in the seperator bottle, there is water in it and the air lining from the 2 liters goes into it. This will create bubbles in the water and can double as a bubble counter.

see pic in link
http://www.plantedtank.net/forums/showthread.php?t=152916
 
#37 ·
So i fixed my problem, definatley was a leak, now the only thing is whenever i have it on it starts to gas my fish, first i notice that they all congregate at the top and start gulping air, thats when i take it out, i have an airstone going and it is producing soooooooo many bubbles, and all i have is one co2 reactor hooked up
 
#38 ·
Here is where a drop checker will be extremely useful. I doubt that you get enough CO2 with that to gas the fish in that size tank. If you have a drop checker, set up correctly, and you are only getting blue green indicator solution, you can be sure you are not gassing the fish, so you will have the courage to increase the amount of CO2 you are adding, possibly by using a more efficient diffuser type. When I first started with CO2 I thought I was gassing my fish, too, but I wasn't anywhere near doing so, as I learned later.
 
#41 · (Edited)
Here is where a drop checker will be extremely useful. I doubt that you get enough CO2 with that to gas the fish in that size tank. If you have a drop checker, set up correctly, and you are only getting blue green indicator solution, you can be sure you are not gassing the fish, so you will have the courage to increase the amount of CO2 you are adding, possibly by using a more efficient diffuser type. When I first started with CO2 I thought I was gassing my fish, too, but I wasn't anywhere near doing so, as I learned later.
And as in drop checker do you mean an extra bottle filled with water where the hose from the bottle is submerged under the water then the tubing that goes into the tank goes into the top of the bottle and not all the way inato the water? because i have that setup running, i have heard that some of the Alcohol (i think its alcohol) from the actual mixture that is created will get into the tank if you dont have that setup

Also sorry for the long explanations, i just dont want to do it wrong, ive got wayyyyy to much money invested in the tanks livestock to take large risks
 
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