Hi all. I've got a too high humidity prob. Rh55-60. 2x2x4' high grow tent. Bud's just flowering. Got my carbon filter above lights. Tube out of tent then re circulates back into another vent blowing cold air back in.. wall mounted oscillating fan, blowing air between top canopy and lights. Got bottom vents open. Top plug vent open during light cycle. Got half cup of rock salt to help. Don't understand why RH is so high? Temp 22
Humidity probs/ set up
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Beehive
Well-Known Member
A dehumidifier is a stand alone unit. It doesn't get stuck in window. There's no duct. I sucks in the room air and spits the same air out dry.
Ducting to the outside of the house is asking for bugs and bigger problems with RH%. In my area, the humidity outside is 72%. I do have a couple of small vents exchanging fresh air in the bedroom. But no pumping it in.
One vent is in the ceiling. Goes to the attic. The other vent is a small opening next to the air conditioner that's sitting in the window.
Humidity has been so bad. The door to the bedroom is open. Inside the house humidity is 45%. Dehumidifier is set on 45%.
Ducting to the outside of the house is asking for bugs and bigger problems with RH%. In my area, the humidity outside is 72%. I do have a couple of small vents exchanging fresh air in the bedroom. But no pumping it in.
One vent is in the ceiling. Goes to the attic. The other vent is a small opening next to the air conditioner that's sitting in the window.
Humidity has been so bad. The door to the bedroom is open. Inside the house humidity is 45%. Dehumidifier is set on 45%.
Renfro
Well-Known Member
What are your intake RH% numbers running? If the air you are using for intake source is humid then you definitely need to look at the dehumidifier route, maybe full on sealed grow.
Renfro
Well-Known Member
This is confusing. You are ducting the humid air outdoors?
No, I was trying to think of ways to lower RH in my tent, so I wanted to know if carbon filter would clean air enough to be recirculated back into another duct hole at bottom of tent. I thought more circulation and duct holes wider would lower RH with more circulation. Looks like I'm gonna have to buy more ducting for intake and just wack filter to highest to create negative pressure? No expert as you've guessed! Lol
RH is 40 during the day. But when lights off and those crappy rectangular vents sealed, fan on its up to 70!! Please correct me if I'm wrong but no light leak during sleep hrs which my issue. My filter is too loud to run constantly.. never mind the smell, neighbours will soon suss by the filter noise!
Oh and invest in ac or dh! :/
pulpoinspace
Well-Known Member
recirculating your exhaust into your intake creates your problem. just exhaust. leave the filter in the tent, have the fan sucking air out the top of the tent, and run the duct from the fan out an open window. either leave the passive intakes on your tent open or make an S-bend with some ducting through the lower socked openings to act as passive intake and block light if you're worried.
no recirculate.
no recirculate.
Cheers mate. All set up, took a while to figure out those rectangular vents aren't for circulation alone they're for looking at yr plants. Altho u need to lay flat to see em thru those things. I'll open the circular ones more, got ducting running from one, onto inside floor. Made a couple of bends to trap light Filter duct now hanging out window. Only got 4 weeks to go on autos so don't want mould at this flower stage, I'll end up burning the whole outfit otherwise lol
Renfro
Well-Known Member
Yeah if you have to close the tent up during the dark period you are gonna have some real problems like bud rot. I highly recommend figuring out a way to keep the vents open and the fan running during lights out. You can build a baffle to keep light out or run duct into the tent.
Yeah I found a way. Intake fan in. Opened the circular vents - 1 at top and 1 on side intake fan. Fixed O ring to make them rigid then fixed nylon fabric over the top. S bend on intake inside to trap light Wont stop all lights but helped massively with lights at sleep plus more circulation. Now 23.5°and 45° RH. Small moisture absorber in there too now. No filter on at the mo either. Here's hopin
Halman9000
Well-Known Member
Howdy ; this is Halman9000 . After I Flush my pots I allow my humidity surrounding the seedlings to decrease to my winter room dry humidity at 10 to 20 percent on seedlings . My theory is that the roots of seedlings won't grow because the leaves will just absorb water from the air if the plant is surrounded by high humidity after flushing the medium . I still have my fan to move air through the plants to make them to respire . My experience is the roots only grow if the plant is forced to get water from flushed soil ( Being forced to get water from the soil and not the surrounding air is what I am trying to do ) . My theory developed after several attempt failures to get the seedlings to grow roots . I also , after a Flush , covering the wet soil will fine mulch in an attempt to increase wicking action to evaporate water from the very wet flushed soil , and add a layer of fine hay mulch to protect my seedling stems from high humidity . Once my seedlings grow I will check the root growth and if roots are growing and the medium has dried to a drier level , I will try raising my humidity surrounding my seedlings back to 40 to 80 percent Relative Humidity (RH ? )
Due to the low RH or humidity , dew point , ? , due to the low humidity and lack of much roots , the fine mulch on top , and the air having a low humidity ( all designed to make roots grow and to avoid mold on stem and leaves) , some of the seedlings start to look like they are shrinking from dryness and lack of nitroge , it still needs a little nutrients , so when I see the seedlings looking dried up I do a light nitrogen + water foliar spray . I could have tried to get nitrogen to the roots , but the fine hay mulch could use a small amount of nitrogen to begin to break down into finer pieces .
I am using humidity dome and have a humidity gauge inside the dome . After doing a light water + Urea ( nitrogen that works good for foliar spraying ; however it has more salt than nitrogen that releases somewhat slower ; which means I have to flush somewhat more ofter due to slightly faster salt build up ) . So I am trying to force the roots to grow and the more I use a foliar spray of nitrogen + water , the slower the roots will grow . However , if the seedlings run out of nitrogen and are starved for water they start to shrink and look less green , then at that point I am forced to due a light foliar nitrogen + water spray to put down a light covering of nitrogen + water onto the seedlings and the fine mulch so that I can close all of the vents on the humidity dome ( 7 inch tall dome ) , and I leave the dome on unless the seedlings and the mulch have time to fully absorb the water + nitrogen foliar feeding . I leave the dome on for about an hour and then slowly open the vents of the humidity dome , in small stages , until the seedlings look vigorous enough to allow more air to flow around the plants to restore respiration ,
The idea is to force the roots to grow , but there is a limit how quickly this can be done . The converse of the if you use a foliar spray of water + nitrogen too often and too much , then the roots won't grow and the plants will get infected with mold and bacteria and fungus and will eventually die .
So I have no choice at this point but use common sense to force the roots to grow , but feed it water and urea only enough to keep it vigorous enough to not die . I am probably making some mistakes due to lack of experience , but I should get better results this time around and with a lot of luck my plants won't die until they flower and run their normal life cycle .
The hard part is right after a flush and the medium is extremely wet ( I flush it alot until the water coming out of the pot is clear ) , At this point if I put it in the humidity dome and open the vents all the way and the fan is pointing at the dome , the humidity is still too high , in the the plant is not needing water from the roots and so the roots aren't growing . So far it seems that when the soil is really sopping wet , I have to either remove the dome or force high speed air through the humidity dome . I do both things , going back and forth . I bought a digital scale , and eventually I will be able to figure out when enough water has evaporated from the pots to go back to a normal humidity use and try to keep it at 40 percent humidity . My pots are starting to feel lighter , meaning the soil is getting less wet . I will start weighing the pots so I can relate weight to soil wetness . I can tell just by lifting up the pot how heavy it is , but I might as well weigh some of the pots with my scale so I can pretend I am being scientific .
Hallman9000
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Quintana
Well-Known Member
Carbon filters remove odor from the air. If you are recirculating your wet/humid air back into your tent through a vent hole, then that will account for you high humidity issues. You need to remove the moisture from the grow space completely when you vent (that's why people are saying to vent outside), don't re-circ any air back into your room through passive vents unless you have some sort of air dryer like an AC unit.
Here's a good video from a manufacturer that talks about Plant Transpiration and RH:
I used to manage an entire state for an HVAC distributor and configured air systems for large commercial growers.
Halman9000
Well-Known Member
P.S. update . I got some Miracle Grow Plant Food Spikes a few minutes ago that I ordered a few days ago because I was thinking that I might be low in Phosphorous . The NPK is 6 - 12 - 6 and it also has some other things in it .
I ordered these because I have been failing to get root growth , So I am doing the best I can with only Nitrogen on hand . I also have some calcium and amino acids . Tried all those so I am going to try these 6-12-6 spikes on a 3 of my pots ( I have 15 pots total growing seedlings ) . I have flushed these pots so many times that I might have flushed the phosphorus out of the medium . I will try three different in three different pots ( 1/3 dose , 2/3 dose , and Standard dose , and I will leave the other 12 pots as is until I see the results from the Plant Food Spikes )
Halman9000