Survey on CO2 concentration before/after lights off

[PeterGwee]

Hi guys, would like to know what is the level of your CO2 just before the lights came on and before the lights went off. Please kindly state whether your CO2 is on 24hrs (DIY or pressurised with manual regulator) or control with solenoid connected to a timer...(ppl with pH controller..not needed )

The reason for doing this survey is because I cannot stick close to the 20-30ppm range during the lights on period as recommended by Tom Barr. This is due to the fact much CO2 is lost during the night as my CO2 injection is off (injection starts only during light on period) --- regulator with solenoid....not much turbulence except for the turbulence caused by 2 AC fan blowing onto the water surface 24/7 to keep the temperature at 28 degrees celsius and below. []

My CO2 concentration is as followed
Just before lights on : 11ppm pH-6.91 KH-3
Just after lights went off : 30ppm pH-6.48 KH-3

Bubble rate at 0.8bps, using ADEC external reactor powered by Ehiem 2233
Note: increasing the bubble rate would cause my after lights off CO2 concentration to be too high!

[bclee]

Peter, I do not see any problem in your CO2 level. Why do you have to be bothered with the before lights on CO2 ppm?

Once the CO2 is turned on the CO2 level should rise to around 30ppm.

BC

[PeterGwee]

Ermmm..the word "just" make a difference? I mean 1 minute before the lights came on, the CO2 concentration is only 11ppm...which I think is on the low side (It takes 10 hrs just to hit 30ppm and then sort of gas off by itself over the night...dropping to 11ppm). Many ppl in aquabotanic mention they had CO2 level of 30ppm the moment the lights came on! (but they are on 24/7)..and then 26-28ppm before the lights went out..showing signs of CO2 consumption..(cannot see that with on/off style huh?)

[bclee]

Peter, it does not take so long for the CO2 to rise. After 1 hour the CO2 should be almost the equilibrium level... in your case 30ppm. CO2 do not rise continually. It will plateau off at the equilibrium level.

BC

[loupgarou]

I've tested once before.
lights on: 6.6
lights off:7.2

[FC]

The CO2 that we pump into the tank is about 2~5 ppm/hr. This rate that we pump is to used to replenish CO2 lost through water surface and plant consumption.

With solenoid control, typically, it takes about 2 hrs to reach the desired CO2 level. To obtain the idea CO2 level at light on while smoothen the CO2 fluctuation, you may try:
1) turning on the CO2 1 hr before your light on
2) turning off the CO2 0.5 hr before your light off

If your bubble count is right, you will get about:
1) 20ppm at beginning of light on (and fan on)
2) 25~30ppm at peak
3) lowest 15ppm at light off (provided fan is off at light off)

[Plantbrain]

You have about what most of my tanks run at. As said here, after a 1/2 to 1 hour the tank is up and running at full CO2 levels. The plants take awhile to get fired up and cranking so this is about right for them also.
All night is fine for folks, I've never cared for the method.
Amano has not either but never said why really. We asked. "In Japan it is Taboo to add it!" Why argue when I agree with him? Heck of nice guy and thinks about the environment and conserving nature. Don't believe any nasty rumors about him. They are not true.

Regards,
Tom Barr

[FC]

PeterGwee,

What is your tank size? I ask because 0.8bps seems too little for solenoid control setup.

[PeterGwee]

FC, mine is a 2ft tank...60 X 30 X 45cm. I test the pH with my pH probe (those that are dip inside the tank constantly...calibrated) and my pH test pen (also calibrated)...both gave same reading..

Morning just before lights "on" : pH - 6.91 KH - 3 (maintain by adding baking soda at water change)

Evening before lights "off" : pH - 6.48 KH -3

I did monitor it a few times....drop in pH per hour is about 0.02-0.08...

Eh...Tom, you mean my current CO2 level throughout the light period is okay with 11ppm to start with?

[FC]

"FC, mine is a 2ft tank...60 X 30 X 45cm."
I see, you have the right bubble rate then.

Try the method suggested for 2 days, then, check at following timings:
1) just before CO2 turn on - will indicate the lowest CO2 content
2) just before light turn on - will indicate the CO2 level before light on
3) just before CO2 turn off - will indicate the CO2 at peak (approx)

Fine Tuning:
Scenario 1:
At above point 2), you get lower than 15~20ppm but you get 25~30ppm at point 3), then, try:
- turn on the CO2 earlier, 1.5 ~ 2 hr before light on

Scenario 2: (not likely for your case)
At above point 2), you get lower than 15~20ppm and also lower than 25~30ppm at point 3), then, try:
- increase CO2 bubble count

And so on, I think you get what I mean. If possible, turn on/off fan together with light.

Please feedback.