02-24-2011, 12:02 AM
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Originally Posted by pirasha
I totally agree..I am just trying to get some insight into how these components are all set up in the grand scheme of things..for example I know the bubble counter monitors CO2...but how does it and what is it connected too...I dunno I have done research on all of these components so I know a little bit on all of them but for some reason they are not all coming together in my head, which is why I am begging for help here.
Also I know about the drop checker...I am currently looking up better alternatives...so if anyone has any suggestions it would be greatly appreciated.
Bubble counter litterally counts bubbles of CO2 passing through the line to the tank. It doesn't really monitor CO2 as much as it "measures" it in a sense. It is simply a plastic or glass vial usually filled with water. The line enters at the bottom and CO2 forms a bubble and rises to the top. Hence the CO2 traveling through the line is measured as a rate called "Bubbles per second" or BPS, How many bubbles pass through the bubble counter each second. Its generally just an eyeballed value, hence not very accurate. It is NOT equal to the CO2 present in the tank. There are SOOO many variables here, such as water chemistry, diffusion rate, uptake rate, gas out rate, ect. The BPS measurement does not correlate at all to the actual in tank CO2 levels. This measurement is left to the drop checker.
The drop checker is a weird glass/plastic shaped device, often a bent teardrop shape. It measures CO2 levels using a pH dependent reagent added to a few mL of water. This is placed in the round sphere "bottom" of the drop checker. When properly placed in the tank air is trapped between the reagent mixture and the tank water. Now the drop checker works on the basis of simple diffusion. You inject CO2 into the tank and it will eventually gas out of the water due to diffusion. Since the drop checker is open to the surface of the tank water CO2 will gas into it. As CO2 builds up in the air inside the drop checker it will want to move into the reagent mixture the drop checker holds. CO2 we know effects pH so it will cause a color change due to the pH dependent reagent. Generally if it turns blue=low, green=good, yellow=high. You can make a drop checker much more accurate by mixing up a solution of water with a SPECIFIC calculated hardness, the most commonly used is a 4 degree Carbonate Hardness solution(DKH). Its pretty simple to make and can give you much more targeted values. CO2 in the tank is measured as PPM or particles per million, much of what I have said is assuming your target is around 30ppm of CO2. If you wish to change your target, you much change the reagent mixture.... Thats where things can get a little complicated. Increasing the hardness of the mixture will give it greater resistance to pH changes, decreasing it will make it more sensitive to the CO2. It has to due with buffering capacity.
Hope that makes sense!