Lowering co2 ppm in dark period

[Lovellybudly]

Hi
Running a small 8x10x8 foot high room , fully sealed enviroment, running at 28.5c lights on temp @ 55% RH and 1200 ppm co2.
All going great but starting to get dead spots on fan leafs that I think is caused by elevated co2 levels durring the night (lights of) period.
Night time co2 levels run at around 800 ppm , any idea how to lower this with out external ventilation ?
Thanks
LB

 

[Granger2]

What's your CO2 set up? If it is timed, have it stop dispensing sooner near the end of the day period. Good luck. -granger

 

[Lovellybudly]

Hi
I use a electronic co2 monitor and a gas powerd co2 generatour , the co2 burner is on a photo cell so only comes on during lights on .

 

[vapedg13]

Hi
Running a small 8x10x8 foot high room , fully sealed enviroment, running at 28.5c lights on temp @ 55% RH and 1200 ppm co2.
All going great but starting to get dead spots on fan leafs that I think is caused by elevated co2 levels durring the night (lights of) period.
Night time co2 levels run at around 800 ppm , any idea how to lower this with out external ventilation ?
Thanks
LB

Co2 is used by plants during lights on...not used during lights off...dont use co2 during lights off it does nothing

For plants with a moderate intensity light the CO2 level required is about 900 PPM. For plants under high intensity the CO2 PPM level should run about 1300 during the lit period. Cannabis does not use CO2 during the dark period. At these levels the plants thrive at a temperature of 31º. Under moderate light they will probably do better at 26º.

 

[Lovellybudly]

Co2 is used by plants during lights on...not used during lights off...dont use co2 during lights off it does nothing

Lol , why do you think I'm trying to lower them in the dark period ?
The photo cell switches of co2 when the room is dark , but the co2 levels are still to high ( the point of this thread)

 

[Lovellybudly]

I think some of the high ppm is due to the pilot light having to be always burning , and it being a sealed room pushing up the levels of co2 when the lights are off .
Venting the grow is not an option .

 

[Treetroit City]

Plants do expel co2 at night as well. Only thing I can think of besides venting(not an option) is to put your generator on a timer and cut it off a couple hours before lights out. See if you can get the levels back down to normal +-300 ppm at lights out and see if it still rises during the night.

Best of luck. I have a feeling I'll be dealing with this soon myself.

 

[Lovellybudly]

This is the grow in this location after a 12 month build so may have to re desighn the room after harvest . Venting involves digging down to the room with a digger and laying a pipe into a disused chimney .
Thanks for the help so far

 

[Ilikecookies]

Switch off the Co2 earlier in the day so the levels are lower when the lights go out.

Plants exchange gases at night and fresh air allows this better, can you not vent somewhat, even if it's limited?
I had problems running a strictly sealed room (plants spotting), and it got better when I turned my Co2 off 3 - 4 hours before lights off, and completely disappeared when I started venting my room at lights out.

 

[noreason]

Night time co2 levels run at around 800 ppm , any idea how to lower this with out external ventilation ?
Thanks
LB

What kind of co2 monitor do you use? Is it a controller or just a monitor? If it's a controller (as I suppose) you may luckily find an option to set the burner stop producing co2 BEFORE the lights go off.
This should help to keep co2 lower.

Said that....I can say with no doubt that high co2 environment during the night does nothing bad to plants. I mean ppm values around 1000.

I would think about a point. Plants do use oxygen. Cellular respiration needs oxygen. We all know an high quantity of oxygen to the root mass mean a faster metabolism (if all other factors are adjusted to support the high O level).
Now the point is: if you burn oxygen to produce co2, day after day without replacing the old air with new one, don't you create a poor oxygen environment? Can if affect plants/harvest somehow? I would think about this...

I would also do at least a couple of air-changes in 24 hours if I had to use a burner. No issue with bottled co2, they do not use oxygen.

Hope it helps somehow

 

[Lovellybudly]

I use a fully programable moniter controler , can't rember the make . The room is a completely controlled enviroment for heat (lights off) air conditioned and dehumidified .running 4.6 kw lights horizOntal and some vertical .
I guess I'm going to bite the bullet and put a air intake and out let in.

 

[Lovellybudly]

I would think about a point. Plants do use oxygen. Cellular respiration needs oxygen. We all know an high quantity of oxygen to the root mass mean a faster metabolism (if all other factors are adjusted to support the high O level).
Now the point is: if you burn oxygen to produce co2, day after day without replacing the old air with new one, don't you create a poor oxygen environment? Can if affect plants/harvest somehow? I would think about this...

I think roots use dissolved oxygen in water rather than oxygen in the air ??

 

[Treetroit City]

I think they use both. This is why plants watered several times a day produce so well. Every time they are watered the stale air in the pot is replaced with fresh air.

 

[Granger2]

Yes, both. And the DO in the water/medium comes from the air. -granger

 

[jackmayoffer]

My co2 always spikes at night co2 is off at night but in a sealed room this happens I have never had an issue the plants don't use it at night.Co2 at night is not what is causing your problem.

 

[Lovellybudly]

Thanks for the help guys
It's only on the largest fan leafs , all other growth is lush green and vigourous and packing on buds . Now starting week 4 of flowering .

 

[vapedg13]

Lol , why do you think I'm trying to lower them in the dark period ?
The photo cell switches of co2 when the room is dark , but the co2 levels are still to high ( the point of this thread)

shut the co2 off 2-3 hours proir to lights out

 

[Lovellybudly]

shut the co2 off 2-3 hours proir to lights out

Tried that with no succes , and now think its the pilot light pushing it up.

 

[siftedunity]

plants use oxygen at night, co2 in the day so id be switching it off before lights out.

 

[noreason]

plants use oxygen at night, co2 in the day so id be switching it off before lights out.

Plants absorb and use oxygen all life long, night and day, for cellular respiration.

When the lights go off, plants can even use more oxygen for an increase rate of cellular respiration due to the absence of photosynthesis, but I'm not 100% sure about this.