I have just fitted my fan to my wardrobe and and fired the whole thing up

When I shut the drobe doors there is a bit of suction on the doors, you can feel it when you open the doors. I hope this makes sence

I have read here that there needs to be negative pressure in the grow space, I take this means there should be no suction on the doors at all.

I have a fan controller which I haven't installed yet, so hopefully I can turn the fan down a bit, which I will have to do anyway as the fan is quite noisy, its a lot noisier than had hoped to be honest.

If its still sucking then I guess I need more intake holes

Negative pressure is what you have. Not enough air being pulled in means no smelly air escape, that's why you want negative pressure.

An excessive negative pressure shows that your inlet may be too small.

Ahh, I see, so how much is too much?

I only notice the suction when the door is about 10mm from being closed and the same when I open it.

Damn that fan is noisy, gonna have to sort that out somehow as I have to sleep next to it

Sounds ok to me, I suppose too much would be putting excess load on your fan - dunno how youd measure that though. Rule of thumb is 4x passive inlets to 1 active exhaust (4 x area).

If your fans sucking ok then I wouldnt worry about it, plants wont notice and youll keep the smell in.

What is your fan size Jakk and how big is your growdrobe air inlet?

Sorry for jumping in but i got/had this prob.
In my room i got 10" out and 8" in, they on a controller turned down to about a quarter at mo, But the other day when checking for light leaks i pulled the door shut and after a min or so i noticed that the balck/white thats on the floor was being sucked up and looking at the walls i could see that the maylar was all pulled out?????
I rushed over to open the door and i could feel the pull and hear this wooooshing coming through the gap in the door
When using a fan controller how do u get the pressure right??? also cab to much pressure have a bad effect on your plants???

A strong negative pressure wo'nt harm your girls in any way but what is your fan size(s) and general setup?Do you have carbon filtration?Also,if you have only one fan,what is your air inlet size?

I thought the rule was 7 times the exhaust, and presumably negative pressure is desirable but less is more until of course you have none, right?

I think Jakk has a little under a 9x6" inlet covered in hood filter and a 150mm RVK from the looks of his drobe construction post.

Hey Doc the answer was in me post m8, 10" out with 10"phat filter and 8"in both systemair rvk's,

My fan is 150mmRVK fitted up to a carbon filter. I have 3 intake holes 1 at 6ins x 9ins and 2 at 7ins x 7ins which is 152 sq ins. The grow area is 3ft wide, 2ft deep and 4.5ft high.

My drobe

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