# DIY Co2 questions



## kilfrg7864 (Sep 22, 2009)

im running the Hagen Mini Elite and a DIY Co2, but i am running into difficulties, it seems like the pressure generated by the CO2 bottle is never constant. Maybe every 5 minutes i get a big spurt of small tiny bubbles coming from the hagen but in the down time there is nothing. 

There is some pressure in the bottle, but it does not feel rock hard. 

WOuld these symptoms all point at a leak somewhere? IM not quite sure where a leak could be i used aquarium silicone on both sides the cap, and the only other thing i have connected is a check valve that i also used silicone on because it started to leak. and drip.


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## Big_Fish (Mar 10, 2010)

I suspect the checkvalve is sticky/staying closed.
realistically there should be only enough pressure in the bottle to overcome: 
1) the checkvalve
2) the water pressure. (the deeper the Mini Elite is, the more pressure required to push co2)

when I was using a GLASS diffuser it was a different story entirely. (this was a big reason why I switched to the mini elite)

one other possibility:
the yeast/sugar mixture is brand new (it takes 24-48 hours for the yeast to multiply to the point that there are enough to produce lots of co2... not likely in this case... once it begins it should put out at least one bubble every 10-20 seconds)

I'd suggest removing the check valve and see if that helps.

I also MAY get blasted for this one...:laser:
but I find the checkvalve to be of little use... it's supposed to prevent the tank from siphoning back into the yeast bottle.... but there's little chance of that happening since the yeast bottle is capped... there really isn't any way a siphon will continue into a closed bottle.

a gas separator/bubble counter on the other hand WILL keep the yeast mix from bubbling INTO the tank though.

remove the checkvalve... if that fixes the issue then think about a gas separator ... Pic attached (not my picture... just for reference RE Gas separator)


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## kilfrg7864 (Sep 22, 2009)

good point on the check valve. Is there any reason to be concerned with water going into your bottle? i would think you should be more concerned with the yeast gunk getting into your tank more than anything.

Also how much pressure should be built up in my 2L bottle? like i can tell there is a little pressure build up, but its not like super hard like if i were to shake up a soda bottle


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## huaidan (Mar 6, 2010)

If you're "pushing" CO2, you probably won't need check valves. I'm using the venturi input on a powerhead to "pull" my CO2, which puts a vacuum on the bottles, contracting them slightly. If the pressure from the powerhhead slows or stops, the bottles will expand to their normal volume, which is enough to start a siphon. This happened frequently, so I placed check valves. Now the flow of CO2 seems much steadier and my bottles don't get flooded.


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## kilfrg7864 (Sep 22, 2009)

Big_Fish said:


> I suspect the checkvalve is sticky/staying closed.
> realistically there should be only enough pressure in the bottle to overcome:
> 1) the checkvalve
> 2) the water pressure. (the deeper the Mini Elite is, the more pressure required to push co2)
> ...


WEll tonight it actually started bubbling at a constant rate!!! But i took it apart due to the check valve being full of water. But i did make a gas separator/bubble counter, however now i am once again not getting any bubbles >< haha. I guess i will have to wait and see if over the next 24 hrs it will start to bubble again!


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## Big_Fish (Mar 10, 2010)

+1 for huaidan ... excellent point about the checkvalve... it IS possible of course to get some tank water into the yeast bottle if the co2 is being DRAWN out of the bottle (like with a venturi) 
which could mess up your mix, but wont siphon the whole tank out.

I'm a little concerned/confused as to how your check valve got full of water... 

the bubbles should resume within a couple hours at the most... 
once the yeast colonies have established themselves, they put out c02 at a pretty impressive rate, so even after having opened the system it shouldn't take long.


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## kilfrg7864 (Sep 22, 2009)

I think it got full of water from when i shook the bottle water splashed into the tube and the pressure carried it into the check valve. BUt yea 5+ hours later and still no bubbles :-/ very strange. I have it set up exactly like you do in that diagram, maybe i should not have included the check valve like you recommended.


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## Big_Fish (Mar 10, 2010)

the only other things I can think of (besides that check valve) is maybe a kink in the hose, or something physically pinching it. 
it's POSSIBLE that the yeast has consumed most of the sugar and simply doesn't have the resources to continue making c02 at a decent rate... 
if you DO remove the checkvalve, (or open the system for any reason) add a couple teaspoons of dissolved sugar into the bottle.
I'm starting to think you've got a couple things happening at once (sticky checkvalve AND the system is starting to run low on sugar) since we have a good idea that there is enough yeast now, if you make sure there's nothing restricting the flow of C02 AND make absolutely sure it's got sugar it WILL bubble within 3 or 4 hours at most.


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## huaidan (Mar 6, 2010)

Just a quick checklist of a few things I can think of:
How old is your solution? How does it smell? Nothing (good if new)? Yeasty (should be making lots of co2)? Alcohol? (Getting old)? Sour/vinegar (not good, replace)? Foul/sulfur (not good/replace)?
If you're willing to try something different, throw a tablespoon of soy powder or milk powder into your sugar solution (not liquid milk it's full of bacteria). Yeast need protein. Maybe a squeeze of orange juice for some vitamin c.
Is the solution itself bubbling, small Sprite-like bubble rising to the top rapidly or regularly? Does it pressurize if you shake it? (Hint: fold over or clamp your tube right next to the cap when you shake it so liquid doesn't get in the tube)
Immerse your tubes in water to check for leaks. Blow through the tubes to make sure they're not obstructed and the check valves are positioned correctly. Blow through the check valves-sometimes they're stuck when they're brand new, but blowing through them will force them open. If sugar water got in the check valve, there's a very good possibility the sugar sealed it. Think sticky mess. Get rid of it if you really don't need it, or run it through with some clean water then blow it out so it doesn't stick.


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## kilfrg7864 (Sep 22, 2009)

my mixture smells yeasty, and if i shake up the CO2 bottle it starts bubbling like mad! however, i pinched the tube right above the bottle and shook it and once i released it water came into the the check valve. When this happened i saw liquid leaking out of the check valve!! which leads me to think there is where the leak could be! Im going to remove the check valve and see what happens! i will report back!


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## huaidan (Mar 6, 2010)

Maybe your bottles are too full. Leave a few inches clearance beneath the cap to minimize the bubbling and spray fouling your tubes.


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## kilfrg7864 (Sep 22, 2009)

well i did what all of you guys said to take out the check valve, and it seems to be working MUCH better! After getting rid of the check valve ~3 hours ago, im getting about 1 bubble every 10 seconds. Should this number increase?? I figured by 3 hours itd be at the highest bpm, which right now seems to hover around 6.


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## Big_Fish (Mar 10, 2010)

kilfrg7864 said:


> my mixture smells yeasty, and if i shake up the CO2 bottle it starts bubbling like mad! however, i pinched the tube right above the bottle and shook it and once i released it water came into the the check valve. When this happened i saw liquid leaking out of the check valve!! which leads me to think there is where the leak could be! Im going to remove the check valve and see what happens! i will report back!


if you had water coming out of the checkvalve, then the chackvalve was leaking... no 'Could be' about it  (assuming this was 'yeast mix' leaving the bottle, going through the tube to the checkvalve and leaking OUTSIDE the checkvalve... you'd get your fingers wet if you grabbed the checkvalve)

huaidan is absolutely correct, there should be at least a couple inches of 'headroom' at the top of the bottle.... that is, DON'T fill the bottle all the way up.

if it's still only putting out 1 bubble every 4-5-6 seconds, I think your mix is running low on sugar.
try this: (JUST to identify that this is indeed the remaining issue)

dissolve 3 or 4 tablespoons of sugar in a small amount of hot tap water (just enough to dissolve the sugar... the amount of water isn't that important... I'm thinking 1/4 to 1/2 a cup)

pour out some of the mix in the bottle (enough that you can add the dissolved sugar and end up with 3-4 inches of room at the top of the bottle)

add the dissolved sugar to the bottle and re-cap.
no need to shake/stir/disturb the mix bottle... just pour in the sugar solution and recap.

after 3-4 hours, you should have at least 15 bubbles every 30 seconds. (probably more like 30 bubbles every 30 sec's)

if not:
1) there's still a leak somewhere
2) the temp of the mix is well below ~70 F.
3) (LEAST Likely) you've got old/weak yeast.

Give 'er a whirl and let us know how it goes. :smile:


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## kilfrg7864 (Sep 22, 2009)

this is very strange, yesterday when i set it up it was working really well, but once i wake up the whole CO2 system seems to have stopped, with almost no pressure in the main 2liter bottle :-/ the mixture is about 2 days old, i added 2 cups of sugar to 1/2 tsp of yeast. I will try to add more sugar in and see what happens tonight. 

As for checking for leaks, is there anyway to check without dissembling the whole thing and throwing out the yeast and sugar mixture?

Also i see the bubbles in the bubble counter/separater however, there does not seem to be anything coming out of the mini elite....possibly a leak?


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## huaidan (Mar 6, 2010)

Make sure your bottles aren't too cold. 25 to 27 centigrade should be perfect.
1/2 tsp of yeast sounds a little small if you ask my personal opinion. Yeast really need protein to reproduce. Without nutrient, the only yeast that are producing CO2 are the ones you put in there. Their numbers won't increase significantly.

If you're afraid to put anything exotic in there ( I'm not ), go ahead and dump a boatload of yeast in there. Generally speaking, the more yeast you put in there, the faster it will produce co2 and the faster the sugar will be depleted. If you used 2 cups of sugar 2 days ago, I don't think it's depleted yet.

So, try dumping a tablespoon of yeast in there and see where that gets you, and keep it warm.


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## Big_Fish (Mar 10, 2010)

I agree, if you began with 2 cups of sugar in ~2 litres of water, after 2 days it should be bubbling vigorously. 

I run two 2 bottles, but I do not dump them each week and start over... I just pour off most of the mix, reserving 1/2 a cup or so of 'old mix' in the bottle and top it off with 2 cups of sugar dissolved in as much water as needed to fill the bottle back to it's original level (I leave about 3-4 inches of room in the bottle) I mix the sugar and water in an empty bottle and shake vigorously (to dissolve the sugar, and to add oxygen... which helps the yeast to reproduce) and pour it back into the bottle on the tank. 
If I remember to, I also add ~ 1 tsp of yeast nutrient. (any of the items huaidan mentioned should also work well.. soy powder, powdered milk, etc.)

to check for leaks, DO NOT disassemble ANYTHING... 

(if you were checking for leaks in a tire, you wouldn't take the tire off the rim, then try to find the leak  )

the system can (and at some point WILL  ) leak anywhere 2 components come together.
but if you're seeing bubbles inside the bubblecounter, begin looking there and examine every connection from the bubblecounter to the tank end of the tube. (for troubleshooting purposes, you may want to pull the tube out of the mini-elite.... not required, it's just easier for me to SEE bubbles than to hear them hitting the impeller)

easy way to look for leaks: get some water and add a LITTLE liquid soap
(remember, it's probably anti-bacterial..... don't get the soap mix on your hands then rinse em off in the tank  ) use a syringe, an eyedropper, even a teaspoon if it's all you have and apply that soap solution to each connection in your system. if you see soapy water bubbling at a connection, that's where a leak is. (we KNOW the leak is probably between the bubblecounter and the tank, but there may be others... might as well check all the connections while we've got the soap solution mixed... )
to leak test something like that sticky checkvalve, (you DID throw that away, right?  )
submerge the whole thing in a glass or deep bowl of water. (again, while the system is closed and pressurized) if it bubbbles, it leaks. replace or remove it.  

check the bubblecounter cap (both tubes) and the seal around the cap. use that soap solution on EVERY connection, including the cap on the fermenter itself.

(and if by chance you've already opened the system up, you can just squeeze the bottle to 'simulate' pressure.) remember, there shouldn't be much pressure in the bottle itself, since there isn't anything besides a small amount of water pressure preventing the co2 to escape into the tank. 
If I give my bottles a squeeze, it feels like an OPEN soda bottle.... not one that's capped. almost no pressure I can feel.

check for leaks, add some sugar, maybe add more yeast (it sure can't hurt) 
and see what happens.


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## wlyons9856 (Apr 14, 2010)

I just today made a DIY CO2 generator, it seems to be working quite well, I have it attached to an airstone and the airstone about 1.5-2" under my gravel substrate, I get a large stream of about 20 small tiny bubbles every 3 seconds, is that too much co2?


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## huaidan (Mar 6, 2010)

Depends how big your tank is. How many big bubbles per minute do you get without the airstone attached? To eliminate the question, you should get a drop checker or learn how to make one.


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## wlyons9856 (Apr 14, 2010)

I have a 10 gallon tank, also should the Co2 run all day/night?


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## huaidan (Mar 6, 2010)

Plants don't consume co2 during dark hours. If you leave your co2 running at night, you could lower your pH to toxic levels or suffocate your fish. So generally, running co2 at night isn't recommended. Sometimes, since I'm trying to carbonate 100 gallons, I leave my co2 running at night if my drop checker starts getting bue-ish, like after a water change. If it's solid green, no co2 at night.

Here's a drop-checkerless co2 test you can run if you have a pH test:

1. Take some water out of your aquarium in a clean beaker/cup/glass. Let it sit in the open air for at least 6 10 hours, room temperature, to decarbonate. Think of how long it takes for a beer or coke to go completely flat.
2. While you're waiting for #1 to decarb, do a pH test on your carbonated aquarium water. Take this from the aquarium after your co2 has been running for at least several hours, preferably a whole day. Go ahead and check it at different times of the day, see if it changes/stays the same.
3. After #1 is decarbed, do a pH test. #1 should be higher than #2. You can get a rough estimate of your co2 level by the difference in pH.

If your water quality is fairly normal (#1 pH close to 7.2), then a #2 pH of around 6.5 would be around 20 ppm CO2.


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## wlyons9856 (Apr 14, 2010)

Thank you for the helpful information!
Shince im using just tubing through a soda cap and airstone at the other end should I just pull the airstone out and let it sit, would that be harmful to me?


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## Big_Fish (Mar 10, 2010)

wlyons9856 said:


> Thank you for the helpful information!
> Shince im using just tubing through a soda cap and airstone at the other end should I just pull the airstone out and let it sit, would that be harmful to me?


If at all possible, remove the airstone and place the (now) open tube below the intake of your filter.
the filter's pump will smash the co2 bubbles into much smaller ones, which will take longer to float up and gas out... result= more co2 is dissolved in the water... which is exactly what we're trying to do.
the airstone will eventually clog, and does not break the bubbles down small enough for them to really diffuse.


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## wlyons9856 (Apr 14, 2010)

Ok, sorry for my ignorance but take out the airstone and put it right near the filter intake?

Also what should I do while the CO2 is not running just simply let it sit outside of my tank?


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## Big_Fish (Mar 10, 2010)

wlyons9856 said:


> Ok, sorry for my ignorance but take out the airstone and put it right near the filter intake?
> 
> Also what should I do while the CO2 is not running just simply let it sit outside of my tank?


Yep, you can just put it near (below) the filter intake so the bubbles rise into the filter intake.
(I just run co2 24/7, but it IS a good idea to check the tank PH before and after adding co2, {as huaidan mentioned} JUST to make sure you aren't pumping too much co2 into the tank. more than ~ 30 PPM can be bad for the fish/inverts)

another option is to use a separate in tank filter/powerhead like the one in this thread:
http://www.aquaticplantcentral.com/...s/44053-tiny-super-efficient-co2-reactor.html

you could then use a timer to turn it on/off at the same time as your lights.
when the diffuser is OFF, the co2 bubbles remain large and simply float to the surface.


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## wlyons9856 (Apr 14, 2010)

Thank you! Big help!


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## kilfrg7864 (Sep 22, 2009)

So i actually jsut took my whole Co2 system out and submerged it in my bath tub, and holy moly! i found that the 20oz soda bottle i was using had a HUGE leak where the cap actually screws in!! so i traded that bottle out for another one, and checked, and there didnt seem to be any leaks!! the Co2 system worked great for the rest of the night, however when i woke up once again, it seems like everything just stopped. I dont know why this is. But it seems like everything works good for a little bit then the next day everything more or less stops. I was getting like 1 bubble /5 seconds or so but did not see a steady stream of bubbles. Im at a total loss here i have no clue whats going on.

Im going to empty out my solution and try another and see if it works, what should the solution look like after a week or so? Mine looked just like a watery opaque solution. No foam, or anything. I couldnt really see any yeast in there either looked like they dissolved mostly? If it sat i did see some small bits on the bottom of the 2L bottle.


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## Big_Fish (Mar 10, 2010)

Ok, just so we're all on the same page..... 
here's a great link (great pictures) RE how to get the tube through the bottlecap without silicone or leaks. http://diyyeastco2.blogspot.com/

Next, IF I understand correctly, it was the gas separator bottle that was leaking? (20 oz
JUST making sure you're still using a 2 litre bottle as a fermenter... )

we need to do 2 things, 1 make sure there are no more leaks, and 2 make sure you've got a good yeast mix.
since a fresh yeast mix is gonna take 12-24 hours, start with mixing up a fresh batch, then check the system for leaks while the mix is starting.

the idea of putting the whole shebang in the tub is a good one... assuming you KNOW you have pressure in the bottle. you can use a bottle of soda/club soda to pressurize it, or just squeeze the bottle while checking for leaks (plug the 'tank end' of the tubing first, of course  ).

Step by step Yeast mix prep: (this is NOT the 'ONLY way' to do this.... but I know that it works well and has predictable results) Read through the whole thing to make sure you've got the idea right. 
we're gonna start/rehydrate the yeast SEPARATELY from the fermenter.

get a paper cup/plastic cup/measuring cup, something to start the yeast in.
into that cup add 2-4 heaping tablespoons of Sugar, and a pinch of fish food flakes (yeast nutrients)
Fill the cup 1/3 to 1/2 full with HOT tap water. STIR VIGOROUSLY (to dissolve the sugar, mix everything together, and to get oxygen in the water) 
when the sugar is dissolved, get 1/2-1 teaspoon of Yeast ready, STIR the mix again to make sure there's plenty of oxygen in it, then add the yeast right on top. DO NOT stir the yeast in... allow it to just float on top of the sugar water.

Let that sit for 45 mins to 1 hour (enough time to check the system for leaks  )
after 1 hour, the top of the yeast mix should be covered with a bubbly/foamy sort of substance.
(THIS is the yeast waking up/rehydrating and starting to eat and reproduce)
if there is no activity, give it another hour.

Next, get your 2 litre fermenter handy.
add 2 cups of sugar and enough HOT tap water to dissolve the sugar. CAP the bottle and SHAKE VIGOROUSLY. (again, we're trying to dissolve the sugar and to oxygenate the mix)

once the sugar in the fermenter has dissolved, you'll want to add enough tap water so that you've got a fermenter with 4-5 inches of empty space at the top. you also want to make sure the final mix is at roughly room temp or a little warmer. SHAKE VIGOROUSLY one more time. (we still have not added the yeast)

Finally, dump in the yeast mix from the cup. just pour it in and re-attach the fermenter to your tank.
ensure the fermenter stays at roughly room temp (no colder than 68F, no warmer than 100F.. place the fermenter in a bucket full of water with a tank heater in it if the fermenter consistently stays below 68F)

within 12-24 hours that sucker will be putting out 30-60 bubbles per minute.... or I'll eat my hat.  
it should continue to put out at that rate for at least 5 days. (should last way more than that.... but let's take one step at a time  )

BTW, the yeast should collect on the bottom of the fermenter... looks like flour has settled to the bottom, and is easily disturbed by shaking/stirring the fermenter. first thing in the morning (after the fermenter has not been moved in 12-24 hours) there should be a noticeable amount of yeast settled at the bottom. 1/8-1/4 inch or so.

depending on the type of yeast you use, you may NOT see anything floating on the top of the fermenter. you SHOULD be able to see tiny bubbles rising to the surface inside the fermenter.
the mix should look pretty much as you've described: opaque, sort of milky white.

BTW, what type/brand yeast are you using?? stick with Red Star Quick Rise, or winemaking yeast if you've got a brew supply place nearby.

And never stop asking questions


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## kilfrg7864 (Sep 22, 2009)

will keeping the yeast mixture at too low of a temp really effect it that much? I dont have an extra heater lying around. right now i am getting few few bubbles maybe 1ever 15 seconds, and there is foam starting to form at the top of the bottle. Its not a constant flow of bubbles, but every so often i hear a bubble being chopped up by the impeller. but its still no where near close to 30bpm, and i do not see any bubbles rising either :-/ i have no clue whats wrong with my thing. I checked for leaks before submerging the system into my bath tub to look for leaks and it seemed to be good at that time. Unless a leak formed from then and now i dont think i have a leak.


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## Big_Fish (Mar 10, 2010)

as long as the temp isn't below ~65F you should be good.

1 bubble per ~15 seconds... is this with a new batch of mix? 
if yes, GOOD. it should progressively get faster over the next 12 hours or so. then it should hold steady for a couple days.


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## kilfrg7864 (Sep 22, 2009)

yea its about 1 bubble every 15-20 seconds with a new batch. However it was created almost 24 hrs ago :-/


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## huaidan (Mar 6, 2010)

kilfrg7864 said:


> will keeping the yeast mixture at too low of a temp really effect it that much?


Yes. Trust me, there's a big difference between 65 F and 80 F. I generally don't go as high as 80, except just to get started. It's too much CO2 and the sugar depletes too quickly, so I keep them around room temperature once they get going.

Check your setup systematically if it doesn't get going. Did you eliminate the leaks? Enough yeast?

I've got 100 gal tank
two 5 liter bottles
2.5 pound sugar each
wine yeast
yeast nutrient

I get around 100 BPM on average


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## kilfrg7864 (Sep 22, 2009)

You know, looking at the 2L bottle there seems to be a TON of small little bubbles popping. I can hear them if i put my ear close to the bottle, but yet the bubble rate still seems slow. Im wondering if somehow i have another leak somewhere which would be horrible since i just checked :-/ If it doesnt start to pick up in the next day or two i will check for leaks again. 

And yea i actually did do my set up as shown with making the hole much smaller than the actual tubing so i could get as tight of a seal as possible.


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## huaidan (Mar 6, 2010)

Leaks are like that. You seal one, then the next weakest point goes. Seal that one, etc.

I took no chances. I sealed everything up with rubber glue and silicone before I even got started  

One big advantage of having "vacuum" CO2 delivery is I sealed all my potential leaks on the outside.


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## Big_Fish (Mar 10, 2010)

one thing I've realized about my setup in particular... 
I keep my fermenters right next to the light ballasts, which get rather warm. 

grab a saucepot, fill halfway with hot tap water and stick your fermenter in the hot water... 
I suspect your Co2 production will increase dramatically within 15-30 mins. (and will stay there while the water is warm)

if it does, you might want to think about getting a cheapo 50W heater and putting the fermenter in water with that heater,
or keep the fermenter close to anything warm (like ballasts)
covering it with a handtowel helps keep the temp up too.


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## kilfrg7864 (Sep 22, 2009)

Actually looking at the 2L bottle i see tons of little bubbles! however the bubbles per second is only at about 5, so i suspect i have another leak some where :-/. Got some midterms coming up so i will have to deal with it later unfortunately.


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