Replacing ventilation system with Co2 system?

You are probably right. I also feel that 3200 dollars is too much.

It will be probably the best idea to first get a cheaper one and if it doesn't do a very good job, then buy another one.

Humidity is going to be the biggest problem in the end of the flowering though. Buds are prone to mold in high humidity, but to my understanding plants love high humidity in vegetative stage.

It would be awesome if I wouldn't need to pay more than 1000 dollars for a dehumidifier.

Going by numbers observed in operations that are doing gram per watt with 70% of area used for canopy, averaging 66% maturity. This includes dehumidification provided by AC in high ambient temp environment with target rh% of 50%


If you're doing less than 4-5 gallons per 1kW light with co2, perhaps your running too cool or growing little biomass.

biomass is the key. Per cubic foot, how much plant you have...

Helmut79 said:

Well, I had 28 plants in a room of 1400 cubic feet.

28 pots x 6 gallons = 168 gallons of coco coir.

I had ventilation, but let's say I didn't. How high would RH go in a sealed room?

99%?

Eventually it will probably max out, but how do I know at which rate does hydrated coir evaporate?

How do I know how fast does it increase RH in the room?

Ultimate question - how do I know how big of a dehumidifier do I need?

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A rough guess is one to two gallons a day per plant. The A/C will take out some, but figure enough dehumidifier for the entire amount. I found with bare bulbs (HID), the A/C alone actually can pull too much humidity out. With vented lights, you'll definitely need a dehumidifier. At lights off, the A/C won't run much. The humidity without any dehumidification will reach 100% and condense out everywhere.

Helmut79 said:

It would be awesome if I wouldn't need to pay more than 1000 dollars for a dehumidifier.

Click to expand...

Craig's list. Or just ask around. I got a nearly new one from a co-worker for $40

Red1966 said:

A rough guess is one to two gallons a day per plant.

Click to expand...

SnapsProvolone said 4-5 gallons per 1000 watts of light.

You're saying 1-2 gallons per plant.

I had 28 plants under 7600W.

4 x 7.6 = 30.4 gallons and 5 x 7.6 = 38 gallons, so according to SnapsProvolone calculations I would need a dehumidifier which has a capacity between 30 and 38 gallons.

According to your calculations it would need to be between 28 and 56 gallons.

56 gallons honestly seems to be too much, so I'll take SnapsProvolone's advise of 30-38 gallons.

To be sure that it will manage, I'll go for 38 gallons per day.

The best offer I have found is 3273 dollars for a dehumidifier.

I hope I will find a better price for it.

I live in Europe though.

Your lights don't put out any humidity at all. I was just going by what water my reservoir drops. 1 gallon a day is the most I've used per plant, but you may be growing trees for all I know. $3273 Seems excessive for a dehumidifier. I wouldn't think prices would be that much different. Ours are mostly made in China. Perhaps you have trade restrictions? Here is a link to the most expensive one at home depot, but you can get a 70 pint for less than $300=> http://www.homedepot.com/b/N-5yc1vZ12le/Ntk-All/Ntt-Dehumidifier?Ntx=mode+matchall&NCNI-5

This is getting interesting.

I have been spending quite some time searching for best offers (capacity vs price) in Europe and I've found:

Dehumidifier A, Dehumidifier B and Dehumidifier C

Dehumidifier A looks like a piece of shit, has a capacity of 24L(6.3 gallons) per day and costs 238 euros (320 dollars). Six of them would give me a total of 144L (38 gallons) of capacity and it would cost in total of 1428 euros (1917 dollars).
144L (38 gallons) per day = 1428 euros (1917 dollars).

Dehumidifier B looks like an industrial machinery and has a capacity of 150L (40 gallons) per day, which is very close to a capacity of 6x dehumidifier B's, but surprisingly it would cost 612 euros (822 dollars) more than six of little ones. Why?
155L (40 gallons) per day = 2040 euros (2739 dollars).

Dehumidifier C says:
1) I have a capacity of 50L (13 gallons) per day which is rated at 70% of RH and temperature of 20C (95F).
2) I have a capacity of 170L (45 gallons) per day which is rated at 100% of RH and temperature of 35C (68F).

What should I be looking at, if my target rate of capacity according to a formula of 4-5 gallons per 1000W of HID light is 38 gallons (144L) per day?

What should I be looking at?