Setting Up a Small Growroom - Environmental Control

Been outta the game for about 13 years, but it's time to get back at it. So, I'm in the process of designing a new grow this month. Here are the details:

7ft x 7.5ft room
RDWC
two plants
dual 3.5ft x 3.5ft SCROG nets
4 - 315w vertical reflectors

The room will be cooled by a small mini split and I'll likely blow CO2. Right now I'm trying to work out the environmental control details. I've gone sealed room in the past, with gas and ran a dehumidifier. I'm hoping to avoid the dehumidifier in this small space (space and noise concerns).

Obviously it would be preferable to go sealed room here if I'm supplementing with gas. But, I'm worried about excess humidity considering that half the square footage of this space is going to be canopy. I've considered throwing the CO2 out and just venting the space continuously. But the area outside the room is going to be hot during a good portion of the year and I'm worried about venting all my cool a/c air out and having temp issues in the room.

I'll be running a chiller, so res temps won't be an issue. I've read that undersizing your mini split just a bit will help better control humidity. But will that be enough in this grow space if I go sealed room? Do you think a dehuey will be mandatory if I go sealed room?

...bump.

Any thoughts to help out this new member?

There is no way around not using a Dehumitifer in a sealed room, as soon as lights out, your humidity is going to spike.

It’s cheaper to cool a large area vs small
You could cool the whole room so your venting in cool air vs hot during the summer

I can’t say enough good about the Quest Dual 105 Dehumitifer. about the same water removal as what it replaced, runs 75% less to do the same job, 1/2 the amps. There are lots of attachments so you can use it remotely and duct into your tent or room if there is no room.

If you plan to do a sealed room I’d use this
https://growershouse.com/sentinel-fuzzy-logic-co2-ppm-controller-cppm-4i

I use that model.

If I was going to vent n run CO2 , or flip flop between sealed n not sealed , I’d use this
https://growershouse.com/sentinel-chhc-4i-digital-intelligent-total-environmental-controller

Bigger is better with mini splits .

i dont think so as long as the mini split stays running and you have no open sources of water to evap from,<<big deal,, the mini split wil act as the dehum,, then if things get higher than you like you can switch the mini split to dehumid,, and the room is 7x7 not big at all,, ,,, as long as you have plenty of air circulation on top and a fan on bottom no worries,,

BigHornBuds said:

There is no way around not using a Dehumitifer in a sealed room, as soon as lights out, your humidity is going to spike.

It’s cheaper to cool a large area vs small
You could cool the whole room so your venting in cool air vs hot during the summer

I can’t say enough good about the Quest Dual 105 Dehumitifer. about the same water removal as what it replaced, runs 75% less to do the same job, 1/2 the amps. There are lots of attachments so you can use it remotely and duct into your tent or room if there is no room.

If you plan to do a sealed room I’d use this

I use that model.

If I was going to vent n run CO2 , or flip flop between sealed n not sealed , I’d use this

Bigger is better with mini splits .

Click to expand...

Totally agree about the night humidity spikes BigHorn, I remember those in the past. Great point.

As far as cooling the area outside of the room, it's large and unfortunately wouldn't be practical. I'm suck with the temp swings in that area.

That Quest dehum. sure looks nice, much better than the dehum. that I bought at retail last go around. The Quest is outside of the budget at the moment, but definitely on my radar for future upgrades. I'm going to take a good look at the controls you mentioned. That's another item on my list that I need to get figured out.

I'm wondering if it might be possible to increase the room ventilation rate during the dark hours to help bring the humidity down. I know it's recommended to turn the room volume over anywhere from once per minute, to once every five minutes during lights on. Any idea on the required turnover rate at night to keep humidity in check? Suppose it might vary with the humidity levels outside the room. But, being in Cal our humidity is never all that high.

CB7guy said:

i dont think so as long as the mini split stays running and you have no open sources of water to evap from,<<big deal,, the mini split wil act as the dehum,, then if things get higher than you like you can switch the mini split to dehumid,, and the room is 7x7 not big at all,, ,,, as long as you have plenty of air circulation on top and a fan on bottom no worries,,

Click to expand...

Great point on the open water sources CB7. I'm going to make sure and plumb my RO and mini split drains directly into my sink plumbing to avoid evaporative water. I like the idea of using the dehumid feature on the mini split, I've noticed that option on a few units. Wish these split units could be better programmed to run different features at different times of the day though. It would be awesome to run a/c during lights on, then dehumid at lights off.

Does anyone think it would be possible to run CO2/sealed room during lights on period, then exhaust the room at a high rate during lights off to keep humidity in check? Seems feasible if the required cfm is manageable.

The amount of air movement needed to keep night time humidity in check will depend on lots of factors.
The 2nd controller will handle all of that.
You can do this, but as you vent into the big space your Rh will increase, depending on the size of the main room n the Rh in the grow , you could get above a good Rh.
If you don’t have a way to exchange the air in the main spot , your asking for mold

SoCal Calyx said:

Does anyone think it would be possible to run CO2/sealed room during lights on period, then exhaust the room at a high rate during lights off to keep humidity in check? Seems feasible if the required cfm is manageable.

Click to expand...

Running sealed with CO2 enrichment during the day and heavy venting during lights off is a good plan. Ideally I think not involving your extra room would be best. Just fresh air in, filtered air straight out.

Thanks for the all the advice. Once I get this room set up I'll follow up on how it works out.