Dehimidification Question

Hello all, hope everyone is having an awesome day.

In the dead of summer here with super high humidity. About to enter week 2 flower. Ive got my AC infnity to engage at 55 RH, and will be lowering this slightly over the next 2 weeks into the high 40s.

However, in the basement, without my dehumidifier running, the external room will rise to 65RH, and as such, the tent will never reach the desired 55. So I have been running my dehumidifier, which is doing the job.

My question is where is all the damn water coming from? I empty the resorvoir 2-3 x daily, and I bet its 2 gal capacity. So were talking near 5 gallons.

Where is this water coming from? Is the device pulling water faster from the plants, requiring me to water more frequently? I am in 5 gal promix with temp of 78, and I am currently watering every other day since they are in stretch mode.

They look fine, just curious more than anything. I presume I would only need to water every 3 days or so, but then I would be facing the 65ish RH level and that’s no bueno.

Thanks in advance!


“ The lower the RH, the more moisture the air can hold, which is why moisture can easily evaporate off your body and back into the air inside your home, where the humidity falls once temperatures rise . During the winter months cold, dry air from the outside can get inside the house.”

Not from me but maybe you understand now. :+1::+1::+1:

I live 22 miles from the Gulf so it feels like being in Hell. The older houses are as thin as a Cracker Jack Box.

There is 18.79 ml of water suspended in a liter of air at 70F/70%RH. If you use a 4 X 8 X 8 tent, that would contain 130 liters of water. That’s 34 gallons of water.


Math isn’t my strong suit, what does this mean lol?

Also, based on humidity lowering if temps rise, I do need to up the wattage but waiting for current heat wave to subside. That would help lower it a bit, also explains why rh spiked when my lights go off.

Thank you all :slight_smile:

1 Like

People don’t really understand RH. Relative Humidity is, well, relative. It is tied to the temperature of the air. Warm air can hold more moisture than cold air (think fog) and the RH number is representative of the temperature. This means that 70 % RH at 70 F contains the same amount of moisture as 78% RH at 60 F. As temp goes down, the moisture content remains but the total percentage goes up. This is one reason you see the rise in RH after lights out.

What I tried to demonstrate to you after you asked where the water comes from is to show just how much water is present in room ambient air. It’s a lot.

1 Like

I would suggest just make sure you have lots of air circulation, my 4x4 tent is in week 10 of flower and is absolutely packed to the brim

A lot of the time, especially after watering my RH will go into the 60’s (%) but It dosent cause me any issues because I have absolutely overkill air circulation. Total of 6 fans. 3 over the canopy, 3 under. Plus the exhaust fan going . so as long as you have the air constantly moving I wouldn’t worry about it effecting things too much

1 Like

I’m one who didn’t understand until you just schooled me. Thanks as always :grin:.

Would putting the device inside make sense or maybe that’s needed when I need that humidity high 40s?

If you have plenty of airflow, being around 50% would be fine. I put my dehumidifier in the grow space at night. I never ran during the day.