According to the standard formula 3*KH*(10^(7-ph)), I have 147 ppm of CO2 in my tank.
All tests unless otherwise stated were done with AP test kits, checked for expiration date.
My KH is 19.5 in the tank. 17.5 out of the tap. City water report agrees, KH is 17.5 and is due ONLY to bicarbonates.
(Why my tank KH is higher than the tap water KH is a mystery I've yet to solve).
My tank pH is currently 6.6. This is confirmed by a Red Sea test kit.
I've also tested my water degassed over night, and it has a pH of around 8.2.
If you solve the equation above for pH with an assumed CO2 concentration after equilibrium is acheived of 3 ppm, you get pH of 8.2.
Again this works out because the target pH of 7.2 to get 30 ppm of CO2 yields 36 ppm of CO2 given my KH of 19.5. The CO2 is 33 ppm using the city water report's KH value out of the tap of 17.5.
So I see basically no reason to suspect that my results or calculations are in error. Slightly off? Perhaps, but generally correct.
I put about 3 bpm of CO2 into a 2' 2" diameter "rex style" reactor, and the plants pearl like seltzer after about 6 hours of light.
The funny thing is my fish are all fine and dandy. A few died a couple weeks ago but since then everyone's been happy, active, eating well, etc.
I thought I would share since 147 ppm of CO2 should be killing everything in my tank.. except the plants of course
(Oddly, I still have very tiny tufts of BBA clinging to my driftwood. The claim that increased CO2 will eliminate BBA doesn't seem to hold. As you may have seen from my thread in the 'Algae' forum I also have a few other kinds of algae but it's minor and not really growing. It just won't go away completely.)