still cant get my temp below 81 since switching to the 400 watt hps. when i was running the mh temps were between 75 and 77. ambient room temps are between 65 and 68. running a 6in inline 400 cfm with air cooled hood in a 3x3 tent. when running the mh i could have the fan dimmed to 50% maybe a lil less and temps would stay perfect. now with the hps dosent matter if i run it at 50% or full power temps stay about the same i have 2 6" intake holes cut at the bottom of the tent one on each side
still cant cool
- Thread starter james21
- Start date
mr2shim
Well-Known Member
Well, you have a 400cfm fan. Your grow space is 3x3. You didn't list a height so I'm going to assume it's the size of most 3x3 tents which is 6'
So. With that out of the way your tent is 3x3x6' or 54 cubic feet. How many times the air should recirculate in your tent in a minute is 3 or 5. I honestly don't remember. So we divide your fans cfm by the cubic feet of your tent. 400/54. So the air in your tent is replaced 7.4 times in one minute. So that says your fan is more than capable of keeping your tent close to ambient temperature. The next thing would be to calculate the intake hole sizes and if they're adequate in size. Quite honestly I don't remember the calculation but I will say that two 6" holes is more than enough, it's probably too much to the point where there is little to no negative pressure inside your tent. This can be seen actually your tent walls will concave.
Honestly, 81 isn't that bad. My tent is usually 84 when I'm in flower. I wouldn't worry about it.
What do you mean cut? Did you cut more holes in the tent aside from the ones that were already there?
So. With that out of the way your tent is 3x3x6' or 54 cubic feet. How many times the air should recirculate in your tent in a minute is 3 or 5. I honestly don't remember. So we divide your fans cfm by the cubic feet of your tent. 400/54. So the air in your tent is replaced 7.4 times in one minute. So that says your fan is more than capable of keeping your tent close to ambient temperature. The next thing would be to calculate the intake hole sizes and if they're adequate in size. Quite honestly I don't remember the calculation but I will say that two 6" holes is more than enough, it's probably too much to the point where there is little to no negative pressure inside your tent. This can be seen actually your tent walls will concave.
Honestly, 81 isn't that bad. My tent is usually 84 when I'm in flower. I wouldn't worry about it.
What do you mean cut? Did you cut more holes in the tent aside from the ones that were already there?
it was a diy tent with panda fil
Slipon
Well-Known Member
yea sumtimes you have to try out different stuff in order to find the sweet spot..
but it sounds a bit wierd to me unless your MH is on less Watt the your HPS ? I was in the impression that MH got hotter ?
and I agree 81F is`t bad just keep some good air circulation in there with a fan or sumthing .. cool the hood from the outside aswell
but if you want them perfect 78F you could try to run some dutching to a cooler room/window etc. to "collect" some cooler fresh air for your intake hole/holes and/or try to lower the ambi temps of the entire room your tent is in ..
and no matter what, you will need a bit of negative pressure in there or smell might leak, specially with a DIY tent, with a bit of negative pressure you ensure all air going out, is through your filter, if you turn your vent off and then on you should see the sides be pulled in a inch or two, tho normally rule of thump is that the intake holes need to be between 2 and 3x the size of the outtake fan, agin sounds weird, I have 3x 4" for my 6" vent on a coolhood and with a filter on in flowering
but it sounds a bit wierd to me unless your MH is on less Watt the your HPS ? I was in the impression that MH got hotter ?
and I agree 81F is`t bad just keep some good air circulation in there with a fan or sumthing .. cool the hood from the outside aswell
but if you want them perfect 78F you could try to run some dutching to a cooler room/window etc. to "collect" some cooler fresh air for your intake hole/holes and/or try to lower the ambi temps of the entire room your tent is in ..
and no matter what, you will need a bit of negative pressure in there or smell might leak, specially with a DIY tent, with a bit of negative pressure you ensure all air going out, is through your filter, if you turn your vent off and then on you should see the sides be pulled in a inch or two, tho normally rule of thump is that the intake holes need to be between 2 and 3x the size of the outtake fan, agin sounds weird, I have 3x 4" for my 6" vent on a coolhood and with a filter on in flowering