Originally Posted by fishmonkey
ok so i saw in a fish magazine about how you can use a ph tester to measure the co2
going into your tank and keep it from overdosing it or something. how can it do that? would it be worth getting one if i got a co2
Please ignore this if the other answers addressed your question, since it is a bit more technical than you may want.
You asked how a pH controller can control CO2
, and that's actually a pretty good question! Here's a quick and dirty explanation:
pH is a measure of how acidic or alkaline something is (actually, the measurement depends on the ratio between hydrogen and hydroxyl ions, but there's no need to get that technical!). So, a pH controller measures (you guessed it) the pH of the aquarium's water. For our purposes, you can think of it as measuring how acidic the water is.
A pH of 7 is neutral, meaning that the water is neither acidic nor alkaline (basic), while a pH less than 7 means the water is acidic (with lower numbers being more acidic), and numbers greater than 7 indicate that the water is alkaline (with higher numbers being more alkaline). Because the pH scale is logarithmic, the difference between adjacent numbers (say 6 and 7) actually represents a 10 fold difference in acidity; this is why aquarists tend to care about smaller changes in pH (say 6.2-6.4).
But you're probably wondering what CO2
(carbon dioxide) has to do with pH, and that's the crucial part of this. When CO2
is mixed in water, one of the results is acid. So dissolving CO2
in water makes the water more acid, and thus lowers the pH. As plants use up the CO2
dissolved in the water, the water becomes less acidic, and the ph rises.
So, the idea is that you set the pH controller so that it turns the CO2
off and on for the desired pH. The end result is that by controlling the pH, one is also controlling the CO2
It's actually a bit more complicated, because the CO2
levels in the water depend on the pH, but that's a bit much for this post. Besides, I haven't figured it all out for myself, yet!
I hope this was helpful, and not too techie!