Humidity droping to 90% at night

So at night the temp drops to like 58 degrees or so and the humidity hits 90%, is that okayÉ The rest of the time the humidity is a lot lower, when the fans and exhaust are going. Thanks.

Mike

keep the fans going all the time.

Then my temperature drops to like 52 degrees though

darkdestruction420 said:

keep the fans going all the time.

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you want to keep air moving all the time. Leave the fans on 24 hours a day. You wanna move air and prevent mold. Your plants need fresh air all the time.

try incorporating a smaller fan.. maybe a pair of fans that don't put out as many CFM's. But use these during 'lights off' times only..

thats what I would do.

I agree with ganja lover here. If you are worried about temps then use a smaller fan at night but there always needs to be fresh air moving otherwise you will get mold and bud rot which will ruin your crop.

akgrown said:

I agree with ganja lover here. If you are worried about temps then use a smaller fan at night but there always needs to be fresh air moving otherwise you will get mold and bud rot which will ruin your crop.

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Cool, so do you guys think i should maybe get a space heater at night to keep the temp above 60É

Mike7 said:

Cool, so do you guys think i should maybe get a space heater at night to keep the temp above 60É

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Wouldnt hurt.

52 is fine, your plants might even like it. Why not just run a dehumidifier, there not that expensive and will hold your RH pretty close to wherever you want it.

that much humidity will cause problems.

i agree, leave the fans on. your buds may turn a little purple if the nights are in the low 50's, but last time i checked, purple buds are better than moldy ones.

Steadmanclan said:

that much humidity will cause problems.

i agree, leave the fans on. your buds may turn a little purple if the nights are in the low 50's, but last time i checked, purple buds are better than moldy ones.

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Lol I know tons of people that will pay extra for purple buds

Steadmanclan said:

that much humidity will cause problems.

i agree, leave the fans on. your buds may turn a little purple if the nights are in the low 50's, but last time i checked, purple buds are better than moldy ones.

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Not to mention the fact that alot of places get down to that or lower at night outside and people grow just fine. my girls brave those and lower temps very often the last month or so of flowering and i havent had any problems ever cept if its gonna be a heavy-mild frost you gotta bring em inside overnight cuz they cant take more than 1 or 2 heavy frosts.
original poster-
Despite that fact my advice remains the same as before, airflow is very important, especially during flower.

Update: Added my dehydrator to the grow room to raise the temp a bit, it was like 68-70 last night, pretty nice IMO, kept my fan on low the entire night and all was good. Didn`t check on humidity, forgot, but assumed it was much lower. Will check again tonight.

Hi mate. i had the same problem when i started my grow. Not realising why this was, i did some research to fix the problem... Here is what i found out and what it was being caused by and fixing the problem. So i hope this help's you as it did with me.

Firstly when your lights are on the heat generated by them will dry the air in the grow space keeping the humidity lower. At night cycle the heat is no longer in abundance so the humidity is not being dried and will stay at a lower level in the grow room. Thus causing buds to rot or on early plant leaf mold. Now i had a couple of fans going at night and a 6" carbon filter. This should have meant that my humidity should have stableised within the room but as the grow went on the humidity became even higher. I started scratching my head again and to look for an alternative solution to lowering the humidity, so i went and got a dehumidifier at a pricely cost. Now me being me. I knew that this would do the job. I put it in the room at night and hey presto it sucked moisture from the room. But somthing still didn't seem right as it only lowered it by 10% ish and for the next few days i monitored the humidity.

After a few days. I started thinking that it was somthing else and to start checking the equipment that i have. This is what i found was the problem.

After checking all fans were working properly i started to check the ducting that was fixed to the exhaust and found that the condensation had built up so much in side the duct that it had created a pool of water inside, this was stopping the humidity exiting the room. So what i did was to drain the ducting, re-fix it with less bends and to get a pin and prick some tiny holes in it where the condensation may collect, so that if water drops do form and collect then they have somewhere to get out from. I put a few towels under this so i could test this method and it worked...

I took out the dehumidifier at night and tested the room and it was bang on perfect on the first test. So if your using ducting it may be wise to just give it a little check to see if there is a build up of liquid...

Sorry this was a bit of a read for you but if there is anything in there that may help you then your good to try it......

Dan

Good advice, i checked into that and everything was fine.

I've only got like 90 sqf, and the guy at a hydro store said i needed this 392 cfm fan, when in realityI am told you need an exhaust that empties your room every 5 minutes, not 15 seconds lol. Is it possible that my low humidity is due to my extremely strong exhaust? Perhaps I should change my timer on my exhaust so it runs on 45, off 15, to allow the humidity to rebound a bit, and then maybe have it run 15 minutes every hour at night time so that it lowers my humidity to a nicer range.
what do you think?

I think you should be running your exhaust all the time. You need to create negative pressure in the room. This means more air going out than coming in. The exhaust pulls hot moist air out and this help's to lower humidity. If you have positive pressure, then the hot sticky moist air will stay in the room and thus could be the problem.

Give me the low down of your room and if you can add some pics and we'll see if we can get this problem sorted out for ya...

Dan

Here's a link to my journal, it's pretty basic so far.

I think I know what my problem is then... What do you think of this, since i clearly have a super powerful exhaust, then using my above schedule should even out the humidity. Ideas?
https://www.rollitup.org/grow-journals/336341-my-first-grow-2x400w-2-a.html

Danthebull said:

I think you should be running your exhaust all the time. You need to create negative pressure in the room. This means more air going out than coming in. The exhaust pulls hot moist air out and this help's to lower humidity. If you have positive pressure, then the hot sticky moist air will stay in the room and thus could be the problem.

Give me the low down of your room and if you can add some pics and we'll see if we can get this problem sorted out for ya...

Dan

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