# [Wet Thumb Forum]-calculating CO2



## Ben C (Apr 16, 2006)

Hey, 

My tank is currently at pH 7.3 with a KH of 3.36. A calculator on another site i found said that this equals about 5.05ppm CO2. 

I find this hard to believe. It seems WAY too low. I've experimented with leaving my CO2 on over night to control pH swings, so thought the level should be MUCH higher. Am aiming for somewhere around 25-30ppm (trying to stimulate glosso into action, for one!). 

Is this an accurate calculation? if so, i assume its safe to crank up the bubbles/minute?

thanks, 

BEN


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## Ben C (Apr 16, 2006)

Hey, 

My tank is currently at pH 7.3 with a KH of 3.36. A calculator on another site i found said that this equals about 5.05ppm CO2. 

I find this hard to believe. It seems WAY too low. I've experimented with leaving my CO2 on over night to control pH swings, so thought the level should be MUCH higher. Am aiming for somewhere around 25-30ppm (trying to stimulate glosso into action, for one!). 

Is this an accurate calculation? if so, i assume its safe to crank up the bubbles/minute?

thanks, 

BEN


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## Roger Miller (Jun 19, 2004)

I get 5.9 ppm CO2. You might get what you want by cranking up the bubble rate. If a low flow isn't the problem then it might not help very much.


Roger Miller


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## Ben C (Apr 16, 2006)

what other problems could it be? if i'm injecting CO2 into a tank with no suface disturbance, what else could it be, but low bubble rate?


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## Roger Miller (Jun 19, 2004)

Bubbles not getting dissolved. If that is a problem then you should be able to tell by looking. What is your bubble rate now?


Roger Miller


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## Ben C (Apr 16, 2006)

hey, there is a steady stream of tiny tiny bubbles. I noticed many of them making it all the way to the surface. Think i might move the outlet to somewhere in front of the filter outlet. 

Good call Roger. Its nice when things make sense!


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## nino (Oct 2, 2004)

Ben, I'm not sure what kind of CO2 injection you use but try placing the output tight underneath or stick it inside your filter intake and let the filter works as reactor. See if this dissolve CO2 better.


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## Ben C (Apr 16, 2006)

Hey Ninob, 

if the current set up (now positioned right infront of the OUTLET) doesn't work, i'll try it by the inlet!! Though i have an internal canister filter, which might be difficult to work with. Will give it a shot tho. Think things are on the mend, as my glosso appears to be growing again. 

thanks ninob


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## nino (Oct 2, 2004)

Internal is even better to dissolve CO2. As long as there are bubbles escaping to the surface, there are cO2 wasted. Just stick the output into the inlet and let the impeller chops up the bubbles


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## Ben C (Apr 16, 2006)

i can't see how i would get the outlet into the filter...? its like a fluval (tho a japanese make.. i believe). How would you get the tubing between the slits in the side of the canister?


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## nino (Oct 2, 2004)

In 2 of my smaller tanks. I cut one of the slit to fit the tube inside the intake.


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## Ben C (Apr 16, 2006)

my CO2 is at 12.7ppm this morning. It was bubbling away over night. Is it really ok to use DOUBLE this amount? it seems like a lot of CO2. 
I juts don't want to kill my fish, thats all!!

BEN


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## Ben C (Apr 16, 2006)

Hey there, 

I've just checked ph and KH this morning, and although my CO2 is bubbling away nicely 24 hours a day, i still calculate only 4.5ppm of CO2. Its seems to be dissolving nicely, and surface agitation in minimal (just ripples, no splashing or anything). Why are the levels so low? I think it explains my somewhat slow plant growth (and consequently still algae). Do i really only have to turn the CO2 up? it still seems like an awful lot of CO2 going into the water. 
What sort of rates do people use currently? i'm worried about suffocating my fish!

cheers

BEN


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## nino (Oct 2, 2004)

Did you still do the same way diffusing CO2 ? 

Bubbles per minute or per second are different on each tank. It depends on how efficient your reactor is and also your water. I run 80 bubbles/minute in my 55gl and get about 25ppm of CO2. In my 10gl, I run 15 bubbles/min and get 30ppm CO2. In my 5 gl, I run 10bubble/min and get about 20ppm CO2.


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## Roger Miller (Jun 19, 2004)

Ben,

Do you have a bubble counter on the system, or are you judging the flow from the bubbles coming from the reactor?

Are you sure you have CO2 in that tank? You can get 5 ppm CO2 without adding any.


Roger Miller


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## Ben C (Apr 16, 2006)

hey, 

yeah! pretty sure! its a canister i bought at the fish shop (the same type they have running their systems) and its labelled "CO2"!! the thought had crossed my mind tho.
I'm just counting the number of bubbles coming out of the thing visually. The CO2 diffuses through a ceramic-like layer into the water as tiny bubbles. This is placed in front of the filter OUTLET, to make sure they are dispersed throughout the tank. I tried putting it into the filter, but the filter seemed to spit out big, noisy bubbles, so stopped that. 

Its making some difference as my glosso has picked up, but if its only batting around the 4/5ppm, theres obviously room for improvement!!

ninob.. no, i bought a pressurised system.. with adjustable tap etc. gave up on the other thing a week or so ago!!


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## Roger Miller (Jun 19, 2004)

Ben,

The bubble counts that ninob and others around here use are from bubble counters. These are devices that let you measure the rate of gas flow by counting fairly large bubbles. You should probably consider installing one. It's hard to even guess what your CO2 flow rate might be.


Roger Miller


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## Ben C (Apr 16, 2006)

hey Roger, 

If you're counting large bubbles, (about the size of a drop of water) then i can do that. I thought the bubble rate was supposed to be the tiny little ones that then dissolve into the water. I can count big bubbles no problem. What would be a good starting rate? 

thanks roger, 

BEN


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## Roger Miller (Jun 19, 2004)

Ninob listed several rates. Take your pick. My tanks run one bubble/second or faster.


Roger Miller


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## Ben C (Apr 16, 2006)

and these are the big bubbles? not the teeny weeny little ones? i guess that's where i've been going wrong!!


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## imported_BSS (Apr 14, 2004)

Perhaps I'm not understanding it properly, but if you have the CO2 just running in front of the Fluval outlet so that the bubbles are being spread across the tank, then it's not really staying in contact long enough to allow the bubbles to fully dissolve.

If the internal Fluval is anything like the one I added to my daughter's 10 gallon (really, it's for her, not for me







), then you might want to attach a "reactor" to the Fluval outlet. The design I use on my 46 gal tank is to attach a 90 degree adapter to the outlet, attach part of a gravel vac to the end of the adapter and then let the bubbles collect within the tube. This forces the CO2 to stay in contact with the moving outlet water for a longer period and gets you better utilization out of the available CO2. Admittedly, with my DIY CO2 system, I only get ppm of 14-17 (pH around 7.0 with KH between 6-7), but the plant grow is decent. I keep thinking about going pressurized with the CO2. It's on the "list"!


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## Ben C (Apr 16, 2006)

Hey BSS, 

sorry, its only a small 13g tank. The bubbles are dissolving nicely, but they usually make it to the end of the tank by the time they disappear. I think my problem has been in the interpretation of "bubbles per minute". Its night now, but will turn the rate up come morning.

thanks for your help, 

BEN


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