Oxygen depletion in a sealed room

Nobodynobody · Nov 4, 2012

For seals room. I use H202 in my water to super charge the o2 in the water. I have heard O2 is useful hit why we never feed when the lights are off... Yes co2 is not needed when lights are off too, and not recommended.

The electronic damper is not what you need. A spring loaded damper so the Co2 gas holds in. The fan will not the electronic damper work fully.

Next would be about your o2. GPS Grow or Sentinel makes co2 controllers. Not the All in one unit, but the co2 ppm controller can be set to Rise or Lower Co2. Then just hook your fan, o2 bottle up to bring the o2 in. You can also get these units to rise the co2 on Normal mode. Fuzzy logic mode is for bottle co2, keep away if your on a burner!

The burners should be blue, if the flam is is not, you can be having other gases that are not safe in the room. For example, a 24,000 BTU CO2 generator requires about five cubic feet (CF) of air per minute of functioning. So if a generator burns for 15 minutes per hour, it requires five by 15 = 75 CF per hour of fresh air. Thus, a 100 CFM fan has to work about one minute per hour to replenish the oxygen supply to ensure complete combustion.

I personally use co2 bottles and have it on fuzzy logic, h202 for the feed. Yhea that is it. Hope this helps.

DX1 · Apr 16, 2013

Great links pussOGbrah. A lot of interesting info from many posters -Thank you! (now I'll be up all night reading). The Ethylene subject is not often brought up but should be.
What effect does too much CO2 have on plants (like 1600 to 2500 range)? I believe that many people use a lot more CO2 than is actually needed or add CO2 when not needed at all.
I have always had the opinion that even sealed rooms need to ventilate to bring in fresh air -even if only at night. Plus if your CO2 sensor uses ABC logic for automatic calibration, you need to bring in fresh air once in a while so the sensor can get a baseline reading (most require a 4-hour period at least every 28 days - otherwise plan on calibrating).
Placement of the CO2 sensor is also very important to get an accurate reading. Wall mounting is OK if you have good air circulation but if you can hang the sensor in the canopy, you will have the best indication of what your plants "see". If you do wall mount the sensor, stay away from corners and other places where air can dwell. Think about the design of the sensor. A plastic case containing the actual sensor which has like one square cm of space for the air to enter the NDIR chamber and that small opening is covered with a "gas permeable teflon tape" that further restricts the airflow but also keep contaminants out. Air needs to flow over the sensor continuously or you will never have an accurate reading.

Damn - I meant to just say thank you for the info...

pussOGbrah said:
Hey racker pretty sure it is ethylene (plus sulfur dioxide). This makes sense because the molecule is to small to be scrubbed by recirculating filters.

After lots of headaches i think i know what is causing the problems in sealed rooms. When the co2 burner comes on in a tightly sealed room, oxygen is depleted. Small plants are unable to make up for the depletion and can't maintain oxygen levels at atmospheric levels (20.4%). With low oxygen incomplete burning of propane may occur causing ethylene and sulfur dioxide to be produced.

In a totally sealed room, their is no room for any combustion by-products besides co2+heat+water vapor. Just because you can breath does not mean oxygen is high enough for 100% combustion.

"Without enough oxygen, complete combustion does not occur. This results in dangerous levels of ethylene, sulfur dioxide, and other gases. Without fresh air, burners shut off when oxygen levels are ≤ 18.9%. Humans begin to experience discomfort at ≤17%oxygen.Oxygen can become depleted in 2 to 3 hours and lead to incomplete combustion when there is no venting and cold night temperatures require continual heater operation (Bartok, 1992)."

That quote is from this article, which is an interesting read for anyone experiencing sealed room issues...
http://www.hort.cornell.edu/mattson/leatherwood/

And,,
http://www.greenhousegrower.com/article/19876/ethylene-in-the-greenhouse

Racker · Apr 16, 2013

When raising co2 levels, the plants stomata tends to close more, making evaporation more difficult. More than 1500ppm is useless for full grown plant.

By calculating VPD you will know or your evaporation is good and stomata is open.

caveman4.20 · Apr 17, 2013

Vpd could do cause the wilting to humid maybe

dizzlekush · Apr 18, 2013

pussOGbrah said:
Hey racker pretty sure it is ethylene (plus sulfur dioxide). This makes sense because the molecule is to small to be scrubbed by recirculating filters.

^^^THIS^^^

Ethylene is one of the banes of sealed room growers. Sealed rooms have to be vented daily to prevent namely ethylene (always a problem but to a further extent when burners are used) and sulfur dioxide (only a problem when burners are used) buildup. The faster your plants are growing, the more ethylene they release. Its active on a part-per-billion level and causes slowed growth rates and flower/fruit abortion in many crops along with other physiological mutations.

Unvented greenhouse heaters and natural gas CO2 generators have been completely phased out of the greenhouse floriculture business in the U.S. and Canada. You wont see either in a commercial flower greenhouse in America nowadays, and that's all because of the ethylene (and to a lesser extend sulfur dioxide) issues that come with the combustion in sealed environments. The phasing out of natural-gas CO2 generators in commercial greenhouses is a more recent phenomenon (last 5 years) since it was originally thought that ethylene wouldn't reach significant levels with high quality generators. More scrupulous real-life testing showed that if the CO2 generator was providing adequate amounts of CO2, it was also providing supra-optimal amounts of ethylene and causing slowed growth rates and and undesired physiological characteristics, and so burners were phased out.

One of the many priorities in creating viable crops that can be grown in space, such as the test crops grown on MIR and ISS, is creating Ethylene insensitive cultivars that can handle the unnatural levels of ethylene that build up in sealed rooms, along with creating dwarf cultivars, heavy guttation cultivars, photoperiod-insensitive cultivars etc.

noone88 · Aug 13, 2014

This shit needs a bump. This is happening to one of my oldest (3 years) sealed room.

Fan leaves look like VPD issues. Yellowing of fan leaves which looks like a cal/mg deficiency across the whole room as soon as you flip to 12/12.

You can finish the grow, but plants suffer. A lot of fan leaves dropping off.

basement bob · Oct 2, 2014

I agree this needs more discussion.

Can I just leave my sealed CO2 room door open with good ventilation while I water every other day?

Or is the exhaust fan on timer every night?

noone88 · Oct 2, 2014

I turned down my CO2 controller (sentinel) to the lowest levels. It fires from 350-700ppm. It seems like the problems have been fixed. I have not tried adding in exhaust fans or other outside-air options.

daub marley · Oct 3, 2014

I agree. It seems like incomplete combustion is the most likely cause. My thinking is that in order to maintain complete combustion oxygen must be in plentiful supply, and in a sealed room that means your burner must always use less oxygen then is produced by the plants. Growing plants constantly change their CO2 intake throughout their life. Without a constant automated monitoring and adjustment of CO2 levels you can never really have a 100% sealed room.

basement bob · Oct 4, 2014

I changed the setting on my Sentinel too. I lowered the ppm to 1000 with a 200 ppm shift. Hopefully this helps.

Bob

MediNice · Oct 5, 2014

pussOGbrah said:
bump

Check your relative humidity. More plants in a room will produce more humidity. More humidity, and the plants are usually more perky.

Just a thought.

noone88 · Oct 10, 2014

basement bob said:
I changed the setting on my Sentinel too. I lowered the ppm to 1000 with a 200 ppm shift. Hopefully this helps.

Bob

You'll need to drop it to the lowest level (350). You're better off with normal levels of CO2 versus the damage caused by the oxygen-depletion / incomplete combustion problem.

basement bob · Oct 10, 2014

noone88 said:
You'll need to drop it to the lowest level (350). You're better off with normal levels of CO2 versus the damage caused by the oxygen-depletion / incomplete combustion problem.

I'll change the settings now.
Thanks @noone88
Should I keep temp and RH @ 80°/60% with the lower levels?

Thanks

Bob

noone88 · Oct 12, 2014

A bit off topic, but i've always found plants to be healthier and grow faster at 70-72 degrees. 60% humidity is great as well.

SHIRDABZALOT · Oct 12, 2014

I don't care what any book says or science states, I flush my room 10 minutes an hr. Plants off gas ethylene gas which significantly stunt growth.....and to the people that worry about dumping a couple bucks In Co2 out of tour sealed room prolly better find a cheaper hobby, cuz that couple bucks a week equals thousands more in product and quality. What I learned in my couple decades of growing is books don't mean shit compared to hands on knowledge! Flushing a sealed room is imperative.

SHIRDABZALOT · Oct 12, 2014

Shit just saw above someone explained it in way more detail! Happy growing guys!

billymirage · Mar 2, 2016

CelticEBE said:
I've never heard of there being oxygen depletion in a sealed room.

Photosynthesis is what occurs with plants. They use co2, water and light and produce sugar and oxygen.

Perhaps by bringing air into the room you dropped your temps a bit. Heat stressed plants can droop.

As stated by a few other people. If you can breathe in the room, there is enough oxygen. Also if there wasn't enough oxygen in the room, there would have been no flame for your burner. Fire can't exist without O2.

It happens and at an increasing rate these days. It is a REAL issue.

fishwhistle · Mar 2, 2016

billymirage said:
It happens and at an increasing rate these days. It is a REAL issue.

Can you explain why its happening more now?Climate change?LOL.

CelticEBE · Mar 2, 2016

billymirage said:
It happens and at an increasing rate these days. It is a REAL issue.

What is happening at an increasing rate?

Plants all of a sudden STOPPED photosynthesis??? They stopped converting CO2 into O2?

billymirage · Mar 2, 2016

people are using more sealed rooms than before... generally very little discussion because it (ethylene/ sulf.) doesn't show up with people using tanks, just NG burners.

fishwhistle said:
Can you explain why its happening more now?Climate change?LOL.

le

Oxygen depletion in a sealed room

Oxygen depletion in a sealed room

Nobodynobody

DX1

Racker

caveman4.20

dizzlekush

noone88

basement bob

noone88

daub marley

basement bob

MediNice

noone88

basement bob

noone88

SHIRDABZALOT

SHIRDABZALOT

billymirage

fishwhistle

CelticEBE

billymirage

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