my humidity readings have been

max 39%

min 0%
what can i do to raise rh levels

i put plant pot saucers in the grow room filled with water,

or a damp towel or get a humidifier.

get a new humidity meter , minimum cant be 0%?

it said -- whatever that means

either way its been way too low

if your humidity meter is reading 0% then there is something wrong with it, so get a new meter before messing about trying to change the reading, if you've got one of those little dial ones from the garden centre then ignore it, you need a good digital meter, picked up a digital max/min hygrostat and thermometer for 20 quid

more air in and less extraction should help

I don't rate any of these approaches personally.

Standing water in your growroom is a recipe for problems. Damp towels? Rather you than me

If your humidity is too low, it is more than likely due to insufficient air exchange. I would recommend a critical examination of your air handling. What are you using for intake/extraction? Where are you intaking from and where are you extracting to?


I doubt it.

What are your temps? Humidity readings are relative to the temperature, they don't mean much on their own.

Not a hydro fan then

I use a mini fogger, although it does sit in a large tub of water

Hope you dont mind me hijacking this post but im also having the same problem, my humidity is around 30%, temps are arond 27, im growing in an xxl homebox, running 2x 600 cooltubes, everything looks to be doing fine. Although im only in 2nd week of vegging, what harm will it be doing the plants and any suggestions on resolving the problem? My exhaust fan is s+p 500 (6 inch) and intake is a 4" s+p (also passive intakes)

bloomin

his humidity meter is probably one of those that read from 30-90 ..so anywhere below 30 it doesnt show anything.

Mine is like that. Plants were doing fine too, but i just added a mini fogger (£15 from maplins). Loads of people on this site use them, i'd never heard of one before. Got my humidty upto the 50's.

I'll only use for a few weeks while they're vegging. It justs sits in water and makes a little mist from the top, works a treat

you dont want to loose negative pressure as the smells will be blown out of the leaks and not sucked through your carbon filter.

Hmmm, well I agree with half of that. But not the other half. Raise both extraction and input. Try and get the air within your grow to be the same as that outside of it. Average household humidity is fine, and if you have good efficient ventialtion that is what should be inside too. But make sure you extract just a tad more than you pump in, as you really do not want to lose your bnegative pressure.
Reducing extraction is a big
Raising imput is fine, but not to the point where you are losing neg pressure.

Why do people always think Digital things are more accurate or better?

Keep your dial - wrap a soaking wet towel around it and leave for 10mins. If it's hit 100% by then, it's working.

I have 3 digital (2 different brands) and 4 standard ones and the standard non digi ones always add about 20% onto the RH, I dont bother with them now the ones I have aint accurate at all.

It won't do any harm at all. If they look fine, they are fine. Most of the time you can ignore humidity, it's only a problem if very high in late flower, or very low for young clones.

my plants are only seedlings

temps are fine min 22 max 28- thats why i cant understand such low humidity

only using passive intake on a homebox xl 1.2m x 1.2m

am i supposed to hold the flaps open or just leave them as they are

because having used both for many many years, i know the cheapy little dial ones to be innacurate, they're ok for a rough idea, so long as you know they were set correctly when you bought it, which more than often they aren't. i don't always believe digital to be better than analogue, but those dial meters aren't analogue, they're just crappy strips of absorbant card that expand at different rates to give a differential reading, where as the electronic meters are factory calibrated and tested for accyracy to within a few percent.
and as his meter is showing 0% which is obviously bollox my point is already kind of proven

that's why.

Where are you extracting to and where is your intake coming from?

1 RVK for 2 600w lights is probably pushing it a little...

what's the temperature of the air outside the tent, if it's much lower than inside and the humidity is already quite low, then once it heats up inside the tent the rh will drop even further, if your plants look ok though i wouldn't worry about it, what type of meter are you using, cos if it's showing 0% rh then it's wrong, full stop

right guys

i have been spraying the walls of my tent to get the humidity uo

i have to turn the rvk off otherwise my rh meter reads LL whatever that means?

is the passive intake enough on a homebox xl

i figure that once the plants get a bit bigger i wont have this problem but its just getting there

my plants are slightly greening up but not how they should be

You turned off your extractor? That won't make them any healtier

If you really want to get your humidity higher try one of them mini foggers from maplins, in a tub of water (with it sitting just below the surface) You got any piccies of the plants?

humidity will have a small effect on growing anyway , temp is more important

no pics m8

i know that turning the extractor is not good but if i leave it on the humidity goes right down

they just have one set of serrated leaves but the green is pale, and dont seem to be moving on

I can't see it being your humidity. What light are they under? How close is it?

I looked in your profile and it says your are in biobizz compost, are they in full strength all mix?

How old are the seedlings?

How do you know it adds 20%, just out of interest?



Cheap little digi ones are inaccurate too, same applies to them - as long as they are set correctly they work. Your definition of 'crappy strips of ... card' is the epitomy of analogue, surely?

You kinda proved my point - 'if they are set correctly when you bought it'.

According to your profile you have a 4" extract and passives

Well imo your exhaust aint big enough for a 600w bulb

That is why your humidity is low

Get a 5" fan for extract and use the 4" for intake

Owd

Low humidity won't kill your plants. Turning off the extractor will. They need to breathe.

If you really can't shake off your obsession with humidity then as Owd says, increase the extraction. But honestly, most strains don't give a damn about low humidity.

so r u saying there should be more air coming into the tent??

my extract fan moves 160m3/hr is that not enough

That's kind of hard to say, as you still haven't told us your temps. But a 4 inch RVK and passive intakes for a 600 Watter in a confined space is going to be touch and go at best.

BTW, are you aware that all humidity readings are relative to temperature? The simplest way to get your humidity up would be to get your temps down, depending what they are of course.

unlikely to have problems in flower just in veg when there is no smell.

YEAH I CAN GET THE TEMPS DOWN A BIT BY TURNING ON THE RVK BUT THEN THE HUMIDITY GOES WAY DOWN??

i really dont get it

sorry for the caps