rolandnguyen
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great info, do you run the fan for 4.5 hours during the off cycle or on cycle? and are you doing all 4.5 hour all at once?I have 20x20x10 cubic ft room when you use the formula to calculate how many cfm this would equate to you multiply the cubic feet by 1.33 which comes out to 5320 cfm. I use 2 400 cfm active air fan with 2 active air dimmer running the exhaust fan speed at 5% and the intake fan speed right around 3-4 %to give me a little neg pressure. 5320/20 Approx 4.5 hours to clear the whole room.
I'm building out a new sealed setup. I originally planned to vent only at lights out to help control humidity. I planned to just hook up the exhaust to a humidistat and let it do its thing during lights off.
I've got 2 flower rooms so want to do some experimenting. One room will run as planned above. Second room I want to burp the room a few times during lights on.
For the second room I assume I will need to scrap the humidistat and use a timer and speed controller for the exhaust fan? I would setup the timer to keep the fan on the entire lights off cycle but how long and how often should I be burping the room during lights on?
Totally makes sense. I accidentally discovered that by injecting fresh air into the room via fan on Hepa filter with dimmer at the lowest setting continuous during the light cycle it’s given best results. In your case it’s the timed fresh air. How did I discover this because we had a room that was hitting amazing results and the room next door was built the exact same way but never hit the numbers like the first room and they were literally next to each other. Exact replicas. So after doing a few thorough examination I found a small hole in the room and I could feel fresh air coming in at a very low rate. So I installed the fresh air system on the other room and bamIf you are having high Ethylene problems, you can use a photocatalytic oxidation device. I Design plenty of CEA rooms and we usually go with the customers request. But we try not to get the rooms to 100% sealed. A little bit of breathing and enough scrubbing makes it so there is no smell, and you don't get too much Ethylene build up. But we've had customers get over 4 LB a light using the rooms we built. But usually you have to use VPD methods, and co2 tanks, or co2 bags. Strains can usually be tackled by raising or lowering the lights for those strains. More indica usually like lights further away, while sativa likes the closer light. If you can't raise or lower your lights, you need to train and plan for where you want your plants to stop growing into flower. However, we do use timers for fresh air, as the more fresh air, the more intense your cooling/humidity/co2 application has to be.
Also I would disagree an RTU is more efficient than a mini-split with variable speeds in anyway whatsoever. Hepa filters would also have to be installed after the unit. Which causes the filter to usually be clogged faster than just recirculating, and HEPA filters aren't so cheap, especially with needed usually sizes exceeding 25"x25"x2" Those are usually $150+ a piece and you'd be replacing them every 2-3 months with outside air, otherwise you'll starve your A/C of air and you'll have problems. Plus ducting is usually not necessary and we try to never use it.
This is why we usually recommend timed fresh air, with HEPA and mini splits. If that's what the customer wants. But either way, we see substantial yield increases in both styles and I haven't seen a lot of the types of problems you've explained, but maybe we're lucky?
I run a vented room 24 hours with co2, and having no problem hitting 3 a light. Genetics + environment is everything. I never cared about the environment before, no comparison now days.Haven’t been here for a while but thanks to all the others that have contributed with more science and also proven it. I simply figured this out from observation in getting different results from 2 rooms built exactly the same.
I run a vented room 24 hours with co2, and having no problem hitting 3 a light. Genetics + environment is everything. I never cared about the environment before, no comparison now days.
I liked your thread on “crac” system years ago.
I run my intake and exhaust 24/7 in the flower room and I use a co2 burner in a lung room. Controlling the environment in the lung room with mini split made for a very stable and consistent environment in the flower room. Propane went up, it now costs me 45$ a grow to run co2.How do you run co2 in a vented room or do you mean you vent your sealed room from time to time? I do vent my sealed co2 room, mainly happens at lights off since my exhaust is triggered by a humidistat.
The speed of exhaust is how I control the humidity in flower room.I run my intake and exhaust 24/7 in the flower room and I use a co2 burner in a lung room. Controlling the environment in the lung room with mini split made for a very stable and consistent environment in the flower room. Propane went up, it now costs me 45$ a grow to run co2.
Thanks for all of the great info this is gold! One question tough - I use 2 AC, one for heating one for cooling. Are you connecting fresh air intake directly to 2 way split AC or you have separate intake for fresh air? If so, connected to HEPA? Do you also connect AC to HEPA before they go into room?Haven’t been here for a while but thanks to all the others that have contributed with more science and also proven it. I simply figured this out from observation in getting different results from 2 rooms built exactly the same.
I use separate intake for fresh air. The Hepa can be passive inside the room on the ceiling. Behind the Hepa you run a duct to an attic vent where you grab fresh air. As your exhaust pulls air out the Hepa brings fresh air in assuming your room is sealed. You have 2 options. Burp the room 3 times for 5 min when the lights are on. Or get a fan dimmer slowly exhausting air out and bringing in fresh air that way. Make sure to use a charcoal filter on the exhaust side and one inside room scrubbing to reduce smell. You can also use a Hepa scrubbing inside room connected to a fan to keep pathogens at bay. The key to weight is stress free environment. The key to quality is sensing at the end. WeThanks for all of the great info this is gold! One question tough - I use 2 AC, one for heating one for cooling. Are you connecting fresh air intake directly to 2 way split AC or you have separate intake for fresh air? If so, connected to HEPA? Do you also connect AC to HEPA before they go into room?
I’m building a system using your advice after carefully reading and considering options. It’s a smaller metal building about 8625 cubic feet (30x25x11.5). So far I’ve got 2, 10 inch AC infinity exhaust fans and scrubbers with smart controls run off APP. 56k BTUs of Mr Cool mini split with 3 air handlers inside and 2 compressors outside. I’ve got 12 1,000 watt LEDs I’ll be installing. One, 320 pint dehumidifier. Two, 50# CO2 tanks. The building came with fiberglass batt insulation so I installed 1x3 furring strips and 2 inch, double sided radiant barrier, closed cell foam board 4x8 sheets them foamed up the remaining cracks and crevices or used seam tape where gaps were tiny or non existent. I also had the metal roof spray foamed with 1 inch closed cell to keep the sun from heating up the metal. I live in Southern New Mexico and it’s HOT AF and dry. Winters are colder than you think out here too. I’m installing a 4in AC infinity fresh air intake fan with variable speed control on my APP. Backdraft dampener along with HEPA filter outside followed by another in line filter box that AC infinity makes as added insurance against pests, mold, dust ect…I’ll run the fresh air intake ducting to one of my mini split air handlers inside placing it directly under the AC to be mixed in. I’m planning on leaving it running on low speed continuously and venting 5-10 minutes every 4 hours. I’m running 4ft x 16 ft living soil beds which dramatically increase CO2 levels naturally. Hopefully cuts down on my CO2 tank usage. Thanks for your help in posting this amazing thread.I use separate intake for fresh air. The Hepa can be passive inside the room on the ceiling. Behind the Hepa you run a duct to an attic vent where you grab fresh air. As your exhaust pulls air out the Hepa brings fresh air in assuming your room is sealed. You have 2 options. Burp the room 3 times for 5 min when the lights are on. Or get a fan dimmer slowly exhausting air out and bringing in fresh air that way. Make sure to use a charcoal filter on the exhaust side and one inside room scrubbing to reduce smell. You can also use a Hepa scrubbing inside room connected to a fan to keep pathogens at bay. The key to weight is stress free environment. The key to quality is sensing at the end. We
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