High RH in flowering.

[PokerToker]

Current setup:

600w cooltube HPS
125mm RVK for outake
100mm Ruck for intake
16" oscilating fan
Envirolite Max/min Temp/RH meter
2 x Humidity Absorbers (using Calcium chloride)

i recently moved 12 plants into the flowering room and under the big light and on 12/12. I was confident that i wouldn't have an issue with Temperature and Humidity because i have a good enough air circulation. The temps are fine but RH is reading Max "84" Min "68" during lights on and Max "--" min "96" during lights off. The humidity absorbers are collecting moisture but don't seem to have made much of a difference to the RH

The Extractors are set on a cycle as they are both extracting air and sucking air back into the growroom from the same boarded window. The Air outake and oscilating fan are on for 45 minutes of every hour then switched off for 15 minutes while the intake is running. If they were both on at the same time alot of the stale warm air exctracted would be sucked back into the grow room by the ruck. All of the fans are off during darkness.

Will this high humidity effect the plants growth rate during the beginning stages of flowering?

When they are in full flower the humidity will increase the risk of mould. Is this the only factor that high RH has on budding plants?

What can i do to lower my RH without having to use a propper dehumidifier that i don't have space for?

Thanks in advance for your help

PT

[LAL]

AHH the classic "--" sign... it means ur hygrometer is essentially fucked...

What are ur temps mate.. because if its saying a temp of say 26-27 then it is highly unlikey to record RH of that degree..

borrow a friends hygrometer and check if im right but im 99% sure u need to buy a new hygrometer.......

[LAL]

right i didnt read the whole thing trhu...

i wouldnt recomend the extraction set up that u have at the moment...

u really need to run the fan at least at idle speed during the night....

and there should defo be no periods during lights on where u have no extraction as that will defo cause high humidity for a period..

a high RH will defo cause rot, but big fluctuations in Rh will also cause... u want to keepo a contant 55-45 during flowering and maybe go down to 30 during the last couple of weeks...

[PokerToker]

i think that the reading "--" on the hygrometer means that the RH > 96%? I've never seen a reading above that percentage.

The temps are max 28 min 26 during lights on. You think that the RH reading is un realistic in these temperatures?

either the intake or outake fans are running during the lights on period. My oscilating fan is on for 45 minutes of every hour as is my outake. are you saying that you Would you suggest having the oscilator on constantly and the extractors on during lights off?

[LAL]

The thing with only running the intake is that ur are in practise letting the humidity rise as there is no extraction...

I dnt like to use an intaKE, i feel it complicates things an isnt really needed for a 600w grow...

I have a very similar set up and use 125 ruck for extraction and then have run 200mm ducting to the coolest place it can go... then just expel the hot warm air back into the the room the tent is in...

DEfinately need to keep the fans running during the night... otherwise they will just sweat...

I would get rid of ur 100 and try a passive set up, running all fans 24hrs and see if that helps...

its defiantely overcomplicated at the moment... btw do u have the lights on during the day? much better to run the lights overnight to get a nive even contant RH and temp over 24hrs...

[LAL]

blimey u running a cool tube aswell. u should defo not have readings like that mate...

can u expalin how ur total extraction is set up please...

[PokerToker]

the warm air is sucked out through ducting from the top of the groom (yet to add carbon filter) in through the cooltube, taken out of the room then expelled outside through the boarded window. The intake just sucks air from the windowinto the grow room and directly onto the plants. When the 100mm ruck is sucking air from outside into the grow room the RH drops about 20%. Without it on the RH would be a constant 80%+

[LAL]

rite... get rid of the 100mm and just run 200mm ducting without intake fan and have the extraction on 24hrs..

the negative pressure created by the 125mm ruck will draw thru so much air thru 200m ducting... a lot more than a 100mm with an intake... ive had very similar probs in the past..

[LAL]

are ur lights on during the night??

[PokerToker]

are ur lights on during the night??

Yea from 5pm until 5am

[LAL]

well. id try what ive said above, or at least get a new hygrometer and see if your readings are accurate...

[PokerToker]

Thanks for your help guys. i'm gonna do some playing around with the fans and hopefully i will get a steady RH. It's not really an issue at the moment because they are only just beginning to show their sex. I think i'll have a few weeks yet to sort it out. I really want to keep sucking air from outside into the grow room as this is providing my plants with some much needed Co2

[LAL]

Mate.. thats what will happen if u replace ur 100m intake and ducting with just plain old 200m ducting...

exactly the same... u will be EXTRACTING warm air thru ur 125mm ruck and u will be INTAKING cold air CO2 rich (negative pressure) from outside...

works on exactly the same principles... try it.. :D

[PokerToker]

Ok i've tried running the extraction constantly along with the oscilating fan (without the intake) and the average humidity has RISEN as the temperature now does not exceed 25 degrees.I'm waiting on another hygrometer just to make sure the RH reading is accurate but i'm pretty sure it will be. I'm pissed off! All of this fucking money i have spent on this setup, all the time it took to build the grow rooms and install everything and now i don't know what to do!

Fucking around with my current setup is not an option now so it looks as tho i'm gonna have no choice but to buy a god damn chunky dehumidifier. What a joke! The results better be bloody well worth all this stress and worry. If not i'm dobbing u all in to the pigs.

[PokerToker]

Well after recieving 2 new hygrometers i expected a big change in the readings and hoped to god that the humidity in my flowering room isn't as high as my original hygrometer read. So i was really disapointed to find that there wasn't much of a difference atall. The plants are on their 3rd week of flowering and growing more and more bud every day so it's pretty crucial that i sort this out so today i went out to homebase and bought one of their 40 quid 250ml dehumidifiers and i was convinced that i'd come home plug it in and my problems would be solved.I've added another 250w RED CFL to the room which is acting as a side light to the 6 plants in flower. I was hoping that this would dry the air out a little also

The new dehumidifier and light have been on now in that room for 7 hours and now the RH is staying at around 68% and the temp is 24c. When the lights go off the humidity will no doubt raise back up to the 80's at least. It's getting desperate now. The white widows are really starting to pack on the bud and i don't know if it's me being paranoid but they seem to have a strong damp smell to them. Things are really getting desperate. It would be such a waste to lose everything due to mould. I need to do anything i can to reduce this risk. Please help!

Just a reminder of my setup:

250w red envirolite
125mm RVK (exaust fan). On 24 hours a day sucking air through a 600w cooltube and a carbon filter
100mm ruck (intake) on during 12 hours of light
small clip on Oscilating fan running 24/7

[marijuanamat]

If your using the same boarded up window to extract and bring fresh air in, then theres your problem.Your intake will be sucking most of the stale air back into the tent so try moveing the intake so it brings air in from the room the tents in as the air will be dryer then the outdoor air.
Try that and see if it sorts it out.

[PokerToker]

If your using the same boarded up window to extract and bring fresh air in, then theres your problem.Your intake will be sucking most of the stale air back into the tent so try moveing the intake so it brings air in from the room the tents in as the air will be dryer then the outdoor air.
Try that and see if it sorts it out.

Yea i noticed last night that the ducting which is bringing air in from outside the window was dripping wet! Immediatly i disconnected the ducting from the window and now air is being taken from outside the flowering partition as aposed to outside. Havent checked the RH since then but I imagine it would have made a little difference but not substantial enough to have solved the problem.

[PokerToker]

Drawing fresh air from inside the room as opposed to drawing in from outside should give a good improvement to RH levels .. you should see them drop nicely.

It will drop a little but unfortunately it is unlikely that it will be enough. I know that the RH has to be a maximum of around 50% but at the moment it seems that it's unrealistic that i will be able to get it to drop that much.

I still have a few degrees to play with so my only option now is to try and raise the heat a little (especially during lights off) with my convector heater and the plug in thermostat that i have. But my setup is already costing me 30quid a week on electricity. I know it's depressing but i might have to face the fact that the cost of growing here just isn't feasable enough. Sucks to be me eh?

[PokerToker]

Sorry i need to bump this as i am really at a loss here and there doesn't seem like there is a solution.

If i was to go and buy a larger more expensive dehumidifier how much electricity is it likely to consume and will it make more of a difference than the one i bought yesterday?

[Couchlocked]

Sorry i need to bump this as i am really at a loss here and there doesn't seem like there is a solution.

If i was to go and buy a larger more expensive dehumidifier how much electricity is it likely to consume and will it make more of a difference than the one i bought yesterday?

that would depend on the wattage wouldn't it?

[PokerToker]

that would depend on the wattage wouldn't it?

Yes but i mean in general do dehumidifiers consume alot of electricity

[PokerToker]

last night i successfully managed to lower the humidity from 75% to 40% during lights on by running a convector heater in conjunction with a plug in thermostat. If the temperature fell below 28c the convector heater turned on and dried the air out. However i had to turn it off again before the lights went out otherwise it would be on constantly during darkness and consume alot of electricity. If only there was a way i could use a seperate setting on the thermostat at different times.

What i am going to try tonight is to run the convector heater off a timer instead. I'll have to work out how long it can be on for before the temperature exceeds 30 degrees and then set that as how long the heater stays on for. During lights off i can experiment with running it for a sufficient amount of time each hour so that the humidity will stay below 60%

Maybe i could use the plugin thermostat and plug it into one of my digital timers? So that the thermostat settings are used during lights on but when the lights are off it comes on for say 5 minutes in every 15? I'm just thinking out loud here, i have to take that pissy little useless dehumidifier back to homebase today, i was considering gettting a larger one but that would take up just as much electricity as a convector heater and would take up a lot more of much needed room in the flowering chamber too. Saying that i could keep the pissy little dehumidifier because it might be useful for when i am drying post harvest. But it's 40quid. £40 is alot of money and i really should be bugetting myself. Oh i don't know! Couldn't someone just tell me exactly what to do to solve all of my problems and make my life hell of alot easier??

Sorry for rambling

[ajgange]

If u have a dehumidifier on you need to get rid of the intake fan and slow down the exhaust fan as much as you can without your temp rising too much. This way the dehumidifier will actually have a chance to do its job, if you have the fans running at high and the air your in taking is at a high rh then you will never solve it with a dehumidifier.

[HughJardon]

This thead is nearly 7 years old mate lol

[ajgange]

Lol oh yeah, don't know y it came up on suggestions then. Didn't look at the date.

[imnice]

Just extract using one fan exhausting out the window and leave the door open in the room so it can passively pull air into tent from elsewhere.
Imnice

[MrChedda.]

Yes but i mean in general do dehumidifiers consume alot of electricity

mines 400 watts same as a shit computer on the go 247

doh i just replied and realise was years old