AquaticTechTank.net

Thanks for the input Ray.

Bad sensor!
I found the fishes wigging out again. I did a quick check and found the sensor reading -600... That can't be right. I had to reset/unpower and repower the board to get the right reading again. I'll have to write some safety code for cases like this.

How exactly are you converting the ppm concentration in the water to the ppmv read by the sensor?

Ive tried for a few hours now to get your 500ppmv =~2.2ppmw in water but cant. You must be using the density of water and density of co2 difference somewhere in there, and also, how are you accounting for henry's law in your code with a factor of 0.8317?

Yeah, show us your math. I'll try to dig up the formulas I went with. 10,000 ppmv to 14ppmw sounds like a low conversion just from experience with co2 in water and seeing signs of fish distress.


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OK ill hand write up my calculations and post as an image tomorrow, taking too long to type up

you might be right about the units. The code is abbreviated for speed so a few zeros were taken out/factored out, here's the real formula


500ppmv = .0005 mole (500/1000000)
.0005 X 44.01 (molar weight of CO2) = .022005 / 1000000 = 2.2005 ppmw

(molar weight/1000 kg/m = ppmw)
1000 kg/m (density of water) = 1000000 mg/l



SO that was the original finding and then I found out about Henry's law. I then multiplied the magic ratio to the CO2 input before converting it to ppmw. I could be putting Henry's ratio in the wrong place. It could go in the end?