Why didnt my co2 level rise?

[secretagent]

I have had a diy co2 system on my tank for over a week now. I have it bubbling into an upside down container that is suction cupped onto the side of my tank. It has been full and bubbling over this whole time yet my co2 is only about 3 or less ppm. Whats the reason it never rose. Does it take longer than this? This is my first foray into using co2.
Chris

 

[rich311k]

First thought I have is do you have an airstone running or a lot of surface agitation?

 

[secretagent]

No airstones, as for surface agitation I have an aquaclear running, but my waterlevel is high enough that it doesnt splash as the water is returned to the tank.
Chris

 

[BlazerFRS]

How big is your tank, and what kind/ number of plants do you have?

Is it possible for plants to use the added co2 so fast the co2 reading remains stationary?

 

[An t-iasg]

What is your KH value? Read here for an explanation of the pH-KH-CO2 relationship.

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

 

[czcz]

Current under the bell will help CO2 enter the water. As long as there is no buffer interfering with th KH pH relationship you will measure change in CO2 from diffusion method very quickly.

 

[malkore]

Czcz nailed it. No current under your CO2 bell = almost no CO2 dissolving into the water. movement is required to carry the CO2 away so it can continue to dissolve into solution.

 

[secretagent]

My kh is 3. CZCZ, the bell is on the back wall of the tank a few inches to the side of my water return from my hob.

 

[czcz]

Try putting it closer and a little over the intake, as most of the water from the return is likely going over the bell. If your rested tap pH is in the 7.5 range, its likely a problem with diffusion method and not some other buffer messing with derived CO2.

FWIW, I no longer use a bell because it just can't diffuse CO2 fast enough and messing with it doesn't help much. Try feeding the line into your HOB intake and look at the numbers. If you want more CO2 or have noise issues, look into a DIY powered reactor.

 

[secretagent]

CZCZ, I see a lot of people here recommend feeding the co2 line into the filter intake. I didnt go this route because it would seem like it would be difficult to tell when your yeast was no longer making co2. Is there something that I missed on that? I will move my bell for now and see if that helps, fingers are crossed.
Chris

 

[czcz]

DIY CO2 requires a schedule and measuring CO2 if you want some stability, and most who use the HOB method probably change the mix well before it stops producing gas. I'm of the opinion that its better to use simple mixes and change staggered bottles weekly (yeast+sugar easily gives two weeks of good output) than it is to run complicated mixes that last a long time, for what it's worth. It sounds like a PITA but becomes easy routine.

good luck,
Joe

 

[rich311k]

I change mine every two weeks. It would probably go 4 but it is easy why bother stretching it.

 

[Zezmo]

Making a DIY bubble counter/gas separator is how you know how much CO2 you are producing.
http://www.qsl.net/w2wdx/aquaria/bigdiyco255.jpg
That link has a nice picture of a complete DIY setup. The gas separator/bubble counter also keeps any stuff from your yeast bottle from getting into your tank.
I went through a bit of a harsh learning curve when it comes to DIY CO2. ;-( I wrote about it here...
http://www.aquariumadvice.com/viewtopic.php?t=63316
With only 3deg Kh, your water does not have a lot of buffering. Be careful about getting too much CO2 and crashing your Ph.
One simple thing you may try to increas your CO2 is to put a "T" in your line. One side you run to the diffusion bell, the other you run to a fine bubble stone. Such as this: http://www.bigalsonline.com/catalog/product.xml?product_id=19793;category_id=1627;pcid1=1623;pcid2= or this http://www.bigalsonline.com/catalog/product.xml?product_id=19795;category_id=1627;pcid1=1623;pcid2=
The bubble stone you put at the bottom of your thickest planting of stem plants. This will have an effect similar to a bubble ladder. Not to mention those stem plants will love you for it.