Heat Problem

I just finished my grow room. I started with 10 bag seeds but due to 8 of them being males/herms I am down to two confirmed females now. I have them under a 600w MH because my HPS burned out and I'm too broke atm to get a new one. Anyways, I just installed what I thought would be a pretty ballin ventilation system. It's a 4' x 4' x 6' (WxLxH) box. I used a hole saw to drill two 6" holes. One near the bottom on the side for intake, and one above the hood for out-take. I used a 6" in-line duct fan for the intake and an 8" inline fan for the out-take.

It was 84 degrees in there (usually hovers around 78-80), and after I turned both the fans on and closed the doors it went up to 85 degrees lol. I was really thinking that would be enough ventilation to decrease my temp by at least 5 degrees but it doesn't seem to be working. Any suggestions for improvement? Here are some pictures of the set up:





I know the humidity is insanely low, I just don't have $ atm to buy a humidifier, but it is coming soon.

A small bowl of water with a small fan blowing over it may bring your rh up. With those fans, i'm not sure why your temps aren't dropping.

Bong Wizard said:

A small bowl of water with a small fan blowing over it may bring your rh up. With those fans, i'm not sure why your temps aren't dropping.

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Thats what the two little bowls in the middle on the floor are for and I have a small fan blowing air in right at the front over them. They are dry in the picture but usually full. And even when full my humidity is only about 25-27%.. still, it helps a little bit I guess.

I'll throw a towel up and see what it does. Thanks for the tip. Also, I going to wait until tomorrow when lights are off and then i'll connect one side of the hood directly to the exhaust.. gonna have to figure out a good way to attach a carbon filter to that but I think you're right since 50% of the heat is probably directly from the hood... Really can't wait for my second batch. Gonna order some feminized seeds of multiple strains for my next round. This batch I was growing while simultaneously building the the room around it and I went without a lot of good stuff like CO2... pots are too small.. dont have a reusable Ph tester yet, and just got my PPM meter.. plus humidity has constantly been like 20-35% the entire grow.. temps fluxing from 60 to 90 depending on the day... This next round I will finally have pretty much everything I need and much better genetics so I'm pretty siked.

This is my first time legitimately trying to grow. I had a few closet ops in the past but they only yielded a tiny amount because basically all I did was water it and give it a little bit of light lol.

I'll let you know if the towel/ ducting-hood vent helps enough.

Thanks again,

-jg

Also, you mentioned not needing the intake fan, but I'm worried that if I remove that, the out-take fan alone wont be enough to contain all of the air in the box and that some of the air/smell might escape through the hole without being filtered properly, so just to be safe I'm going to leave it installed.. especially since its already set.

You cant be that broke to buy an hps if you own a 6" hole saw. I kust purchased one at home depot the other day for 40 dollars I put it back on the shelf twice before I bought the damn thing thinking I would just use my jigsaw....I caved in though!

thinn said:

You cant be that broke to buy an hps if you own a 6" hole saw. I kust purchased one at home depot the other day for 40 dollars I put it back on the shelf twice before I bought the damn thing thinking I would just use my jigsaw....I caved in though!

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ahahaha oh man I know that feeling. I have a old jigsaw too and I was like "fuck well I guess I could just drill a hole and do a sorta shitty, not-perfect hole... or I can buy this $38 drill attachment to make 2 holes with... lol.. Kept picking different ones up, then staring at the price.. then putting it down.. finally on my 2nd trip back to the hardware store I finally caved too lol... just wanted that perfect hole too badly. I feel ur pain bro.

EDIT:

Also yeah I am not crazy broke.. I actually got a second job and gave up my Fridays and Saturdays specifically so I could fund this lol. But I got a lotta bills too and always need to be super careful and conservative and plan ahead. And I just bought that hole saw, ONA odor gel, some active yeast to create co2, carbon filters, and the 8" in-line fan ($35)... so I gotta wait for the next paycheck or two. I had a bunch of the equipment (hoods, bulbs, etc) from a previous attempt I had with some roommates a long time ago.. But since I am taking it seriously now, I've spent a good additional $400-450 on supplies in the past month and a half =/

unlucky said:

​ps, to get your rh up just hang a wet towel in there as simple as that

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I have been scouring to find a method to bring RH up without buying a space stealing humidifier. If this simple, yet possibly genius idea works for me, I'll be back to +rep you again. Thanks! As soon as the lights come back on, I'll try this. Incase you see this before then, what sort of % increase would you expect from a 36"x20"x62" tent with quick air exchange and temps ranging from 73-76F?

That was my biggest problem. I had a humidifier in the tent and was able to keep rh at a steady 45 til i turned on the fan and filter now it sucks it out and rh stays at 18-25%.

thinn said:

That was my biggest problem. I had a humidifier in the tent and was able to keep rh at a steady 45 til i turned on the fan and filter now it sucks it out and rh stays at 18-25%.

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That was one of my concerns with getting a humidifier. And the bucket of water with a fan on it did vrtually nothing in my tent. Some rockwool soaked in a container will slightly help for a few hours, but the fast air exchange dries it quick. Looking foreward to trying this towel trick.

I've been trying it for the past hour now and my humidity hasnt increased at all. I do have the doors open a bit which may be allowing too much air in and out so I can't rule this out completely, but so far not looking like it'll do much for me =/ I'll try it again once I have my outtake connected directly to my hood so I can keep the doors to the room closed without it getting too hot inside.

why is 85 degrees too high? At peak noon day sun it seems perfect to me.

where in a natural growing region for Cannabis does anybody see a temperature below 85 in full noon day sun?

jollygreen said:

Also, you mentioned not needing the intake fan, but I'm worried that if I remove that, the out-take fan alone wont be enough to contain all of the air in the box and that some of the air/smell might escape through the hole without being filtered properly, so just to be safe I'm going to leave it installed.. especially since its already set.

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With that small of room 4x4x6=minimum 115 cfm exhaust. Add another 5-10% for the light, ducting and passive and a exhaust cfm of 200 would easily take care of issue. But the more cfm the better as long as cfm's are enough to maintain negative pressure to kill all smells as long as carbon filter is used.

I don't have a pic of my old veg room which had a passive intake, it now has forced, but here is a picture of my dry room. Note the furnace filter at the center bottom which I use as a intake on the dry room, I used the same set-up except filter was at side of veg room room down low opposite corner of exhaust up high. Filter and opening is 20x14x1 thick". That was enough of an opening with the filter(cheap 1-2 dollar furnace filter) for my exhaust fan which was 250 cfm, to suck in enough air for a room very similar in size to yours. The only reason I sealed it up and now use forced is because I needed that room dark as there is a flower room in the same bedroom as the veg room.

Dry room with furnace filter at bottom center-

View attachment 2582134

veg room with forced intake, you can see the square area where passive filter once was top left corner of pic

When you can afford a humidifier, a cool mist only runs around 40-60 bucks, place it outside of the grow room somewhere near or around the intake, this will allow the grow room itself to keep a higher RH rather than placing the humidifier directly in the grow room where it's immediately sucked out. Be sure to use distilled water or filtered water, not tap, unless you want minerals all over everything.

PurpleBuz said:

why is 85 degrees too high? At peak noon day sun it seems perfect to me.

where in a natural growing region for Cannabis does anybody see a temperature below 85 in full noon day sun?

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For veg it isn't the end of the world but once flowering and even in veg, 75-80 is where this plant grows the best. Unless you are using CO2 85 is quite high for a indoor grow. The potency and yield at temps under 80 is positively noticeable compared to temps over 80. I started with high temps and tweaked my rooms to be 76-78 day 64-68 night and the difference is all positive.

Rancho Cucamonga said:

When you can afford a humidifier, a cool mist only runs around 40-60 bucks, place it outside of the grow room somewhere near or around the intake, this will allow the grow room itself to keep a higher RH rather than placing the humidifier directly in the grow room where it's immediately sucked out. Be sure to use distilled water or filtered water, not tap, unless you want minerals all over everything.

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Another good idea I hadn't thought of. Thanks for sharing.

PurpleBuz said:

why is 85 degrees too high? At peak noon day sun it seems perfect to me.

where in a natural growing region for Cannabis does anybody see a temperature below 85 in full noon day sun?

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Well it is just hitting spring and its still a little chilly outside... so I imagine in about 3-4 weeks when its 30-40 degrees hotter outside regularly that my room will heat up a bit more too, so I don't want to be in the position of it hitting and sitting at 90+ degrees in my grow room, but maybe I'm being paranoid. Also I have to hook up the exhaust to the hood which like unlucky said, will probably bring down the temp quite a bit.

jollygreen said:

Well it is just hitting spring and its still a little chilly outside... so I imagine in about 3-4 weeks when its 30-40 degrees hotter outside regularly that my room will heat up a bit more too, so I don't want to be in the position of it hitting and sitting at 90+ degrees in my grow room, but maybe I'm being paranoid. Also I have to hook up the exhaust to the hood which like unlucky said, will probably bring down the temp quite a bit.

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thats makes sense 90+ seems over the top. I'm sure PM doesn't like it either.