Humidity Problem!!!

[smoka2404]

Hi all,

I'm new to this site,so I'm not 100% up to scratch with how to use it exactly,so you might have to bare with me a little!!

The problem I have with my grow is high humidity.

My GR is situated in my loft,is about 7' long,6' wide,and is about 7' tall along the centre of the room (as the roof is pointed ).It is kinda wierd shaped,like a pentagon (5 sides?) because of the way the beams and joists are positioned to hold the roof up.

I have 2 x 5'' in-line fans working.

One of the fans is connected to a carbon filter,which is extracting hot air from the top of the room,and venting it outside.The other 5'' fan is pulling fresh air in from outside,through a vent in a room,on the top floor of the house (had to cut a hole in the top of a cupboard to get the 5'' ducting down through the roof and attached onto the vent).

I also have a 9'' fan mounted on the roof of the GR,circulating air around the room.

The inside of the GR is covered with Mylar on the roof and 3 sides.The other end wall (which was built with fibreboard) is painted white.

The growing setup I am using is 2 hydroponic systems (not 100% sure of the name of system) .They comprise of a water reservoir with a tray on top,covered with spreader mat.The rockwool cubes sit on the tray,and water is pumped from the reservoir,up onto the tray,and runs down the tray back to the reservoir in a cycle.There are 2 separate tanks,one is 4',the other is 5'.

I have a water heater and an aquarium air pump in each reservoir,along with a water pump.

Both the tanks are covered with a black plastic cover that came with the tanks and all the rockwool cubes are also covered to stop algae growing on them.

The 2 lights are a 400w HPS and a 600w HPS,both with growlux bulbs.

The lights are on at night and off during the day (12/12) to try and keep the GR temperature as close as possible all the time.

I have approx 12 x Acorn and 1 x Heavy Duty Fruity from TH Seeds,and they are about 2 weeks from harvest (if you would like pictures, I can try and put them on later,but as I said earlier,I am new to this!)

I had not really been keeping a close eye on the temperature or humidity which was my mistake.

The GR temperature is approx 60F when lights are off and 75F when on.

The humidity was at approx 80% when lights were on,and 100% when off.

I went out and bought myself a dehumidifier from B&Q for £75,and stuck that in the GR.Humidity now down to a continuous 75%.

I checked humidity of air being drown in from the vent and it was about 70% too, which was also quite high.I disconnected the ducting from the vent and tried pulling air from the 2nd floor of the house but still have no joy.

Can anyone please give me some advice as to what to try next (if you can be arsed getting this far down my letter),as I have nearly ran out of ideas (and money)

I have tried to give as much info as possible but if their is any more you need to know,I'll try and give it to you!

Cheers guys,look forward to hearing from you (if this works)!!!

[Owderb]

seems strange at them temps the humidity is so high

Av u checked that your humidity reading is showing to be about right(hygrometer i think)

just a thought

[smoka2404]

seems strange at them temps the humidity is so high

Av u checked that your humidity reading is showing to be about right(hygrometer i think)

just a thought

286361[/snapback]

Cheers for takin time to read the letter m8,did ramble on a bit.

Yeah I've thought the meter could be faulty,but I could see condensation on the mylar so thought it must be right eh.

Since I bought the dehumidifier and put it in the room,the humidity has went down to constant 70-75%,and the condensation has disappeared completely.

I also have another problem,which is mould growing behind the mylar!!!

But it is all sealed out of the GR (hopefully)!!!

I might go and buy another meter eh!

[Sid]

i had simalar probs, basically my problem was were i was drawing air from, inside the house from a downstairs room is not really fresh air, and can be quite humid. I fixed an inlet vent from the eaves of the roof, so i am drawing fresh outside air into the g/r, i updated my fan from a td/160 to a RVK (160mm) which tripled the input, i now use the td/160 to draw out and a bog standard bathroom extractor to extract, with 2 x oscillating fans, my R/H now sits at a constant 50%, bang on

[smoka2404]

Thanks Sid,

Do you think the fan is struggling to pull the air from the GR because of the carbon filter (not extracting enough air).

I dont have a thermostat/humidistat to control it.I have the fans on for 4mins,off for 2mins when light are on.

When lights are off,the fans only come on in 15min intervals to keep the temp from dropping too much.

The weather has been very wet here recently,so humidity will be quite high naturally I think.

I will try and get photo's up!

[Sid]

My fan ( bathroom extractor one) is on constant when lights are on, and on for 15 off for 30 mins on lights off, my rvk inlet and td/160 outlet are on constant, non stop, my oscillating are on constantly too.

i have no filters at all, as i find the smell tends to go up and out. The only time smell is a prob is come crop time. Im lucky as one neighbours house is a giro drop, and empty, and the other is a fellow toker, who knows nowt about the g/r, but any smells are explained away to personal use, by me and mrs sid.

[Sid]

with regards to the mold, i would def say it is not enough air circulation. if your getting mold behind mylar, watch out for it in your buds!

Peace

[smoka2404]

The mould is a bit of a worry,but I have sealed everything up as best I can,so I can only hope now!

After the lady's are chopped,I will pull down the mylar and give the place a good wipe down.

As for the humidity,I was wondering if you could explain the difference in your 2 160mm fans (the td and rvk).

I just know that my 2 fans are in-line fans!

Sorry if I sound dense!

Do you think the air pumps or water heaters in the reservoir could have anything to do with it?

Cheers m8! (sorry if reply took long,was watchin drugland on beeb 2).

[Sid]

Watching it myself too m8

Sorry i cant give any advise on Hydro as I am a mud grower, but I should imagine if you have a humidity prob anyway ,then a res full of water in your G/R is not going to help much.

as for my fans, the td/160 i have is a 4 inch which shifts 160 m3 of air an hour, my new one, the RVK, (which is just a model number/code) shifts about 475 m3 an hour, so the numbers speak for themselves, as i say the bigger one is drawing fresh air in, so there is a constant good supply of fresh air coming in, this blows through an oil filled rad, which heats the air somewhat, and cuts humidity slightly, then in front of the heater i have a monster oscillating fan which blows the warmed fresh air round the base of the plants, my second oscillating fan blows in line with my 3 x 400w hps lights, to keep a cool flow going through the lights, then my extractor (bathroom is on opposite side of lights pulling the air out into loftspace, this incidentally is my drying room, so i have a constant warm air extracting from g/r into d/r, and finally my ducting from the 160 is above the lights taking all the stale hot air out into loft space again. I tried a dehumidifier once, but i draws moisture from everything in the room, leaves, reservoirs, soil, so i binned that idea, and the air circulation alone seems to have solved it

[Owderb]

if your res is in your growroom you shouldnt need a heater in it,it will be fine.

[smoka2404]

Cheers m8,

I'll take the water heaters out.

Do you think the air pumps in the reservoirs would matter to the humidity?

I think the main problem I have is that I can't draw any dry air from anywhere,as the air outside is about 70% humidity,the air in my house is about 75%,and the air in my loft is about 80%.I can't win...........can I?

I looked at the fans,the intake is a TD125 pulling air from outside,and the extractor is a RVK125 pulling air through a 5'' carbon filter.

Also a 9'' oscillating fan hanging from roof.

It's been raining loads up here the last few weeks m8!

[Owderb]

no leave the air pumps in.They are really important to the water

[tony2wheelsgood]

you're stuck with the humidity of the ambient air unless you feed the intake through a dehumidifier but that's a hassle, i'd try leaving the fans on 24/7 for a start. stick a heater in if you're worried about lights off temperatures, you can get 60w space heaters for not much. just a long tube you stick where you want.

the mould on the walls will need 10 percent bleach to wipe/spray it down. This time of year there are alot of botrytis (mould) spores around from all the rotting vegetation so it's going to be in your growroom too.

[Guest nigfis]

Tony's got it. You have to keep that air moving mate or you'll never get the humidity down. A climate controller would do wonders for you. Adding a heater to prevent cold spells will also be vital.

Don't despair, you can cure it.

[smoka2404]

Cheers Tony,all advice is much appreciated m8!

I think I'll just have to keep a really good watch out for the dreaded mould and keep my fingers crossed eh.

I lost about 2 oz of my last crop to mould but made some A+ bubble from it as it wasn't destroyed (only really got mouldy as it finished drying).So not really a bad thing in the end as I now have the sacs if it ever happens again!!!