Need help with growbox ventilation and heating problem

Hi all,

I made a growbox with insulation using styrofoam, becouse the growroom is not heated and insulated and in there are near freezing temperature at this time of year, well i made an intake hole and exhaust hole with fan, which i didn't yet turn on, becouse it already sucks the air, as heat rises, and it was still too cold, so i closed the intake hole with styrofoam, so less air comes now.
So.. My growbox is less then 2cubic meters big, i use 400w hps mh/hps switchable.
Temps with hps are ok, got 32°C also before, but last evening i left it on(was playing with hole), and today in the morning after 12hrs on it was around 26-29 i think, i dont remember exactly now, i just know it was in acceptable range So that is good, but if i would leave it off for few hours temps would drop at...last time it was 3°C as i was testing...So i bought oil heater, very small one, i was looking for lowest wattage i can get in my location, so i got 300/500/800W, and i put it on 300 in hope it would be enough, after more then 10 hours room was heated on 21-24(I have that thermometer which shows in and out temps, so at wall it was 21°C i think, and around 40cm under light 24°C..-Without any fans)
Thats good, my question is how much fresh air do i actually need to get in the room for plants and how much can i seal up the room, for lower power consumption using thermostat on heater..
Should i set up co2 gen.? In one of our growshops i saw some co2 tabs.. http://www.nomercysupply.nl/nomercy/node/766 any ideas, experiances with that?
And my last question, i don't have pH meter, and i dont know what to search, are there specific soil pH meters, or how do you actually measure?:S I was growing before, but never had one becouse i dont know which will be the right one and whats the process.. Adwa pH meter AD-12 is offered at one growshop online. Is maybe every dig. pH meter good? As mostly it says for water, pools, aquariums and so on..

Rush

anyone??? please? I made a mistake writing about temps 40cm under light..i meant in the air in box no light..i have that tester hanging from light reflector.
And i have one more problem.. I think i will have a little trouble with space, so it would be best if i could leave the door open for minute or two(for example when watering..) but temps would drop instantly.. Do you think it would harm/shock the plants?

If you are not supplementing with co2 I believe the rule of thumb is to recycle the air completely every 5 minutes. There are formulas out there if you search. Try searching "cfm room size" or something.

Disposable co2 Seems like a reasonable practice to supplement a small grow since u can't regulate it if it is cheap enough. Not an ultimate solution in your circumstance. In fact your oil burning heater almost definitely creating co2 just too bad it's at lights out and not helpful. Without some sort of expensive controller I'm not sure how u could take advantage of that.

In regard to your PH meter question one of the best benefits of using soil is that if you use a good one you don't really have to worry about PH. I grow in soil and use one, but barely. With RO water and GH cal/mg my water always gets perfect ph. I did buy a $12 Chinese eBay ph meter. It does work I've even calibrated and tested it with solutions. I did short it out once by accidentally submerging it, but after a few days it started working again. Make sure to only dip the tip. I also bought a cheap ppm meter too that works, I think they sell combo meters too. But back to PH, if you picked a well balanced soil mix you can safely use tap water with much success assuming u also use well balanced nutes if any. I would personally go with the cheap meter though or a liquid test kit. You may hardly use it after u get an idea what your water ph is and get used to how to adjust it, it shouldn't fluctuate much.

Rush56 said:

anyone??? please? I made a mistake writing about temps 40cm under light..i meant in the air in box no light..i have that tester hanging from light reflector.
And i have one more problem.. I think i will have a little trouble with space, so it would be best if i could leave the door open for minute or two(for example when watering..) but temps would drop instantly.. Do you think it would harm/shock the plants?

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To minimize having to open the door to water maybe come up with a drip system where u pour water in though and outside hole and have it flow into your plant. Just close the hole when u r done. U have to have a good idea how much your plant needs tho to prevent over watering. Maybe one of those moisture meter sticks you stab in the soil, u can peek through the watering hole at.

Also if u are bored, have sex with the styrofoam hole.

It is not oil burning heater, it is electrical oil heater.. I was wondering if it would be enough air if i have mostly closed intake hole so little air is circualting and just open the door once a day?
Thanks..

put a heater in your box, on a timer. ventilation is a must. little ceramic heaters are good.

Rush56 said:

It is not oil burning heater, it is electrical oil heater.. I was wondering if it would be enough air if i have mostly closed intake hole so little air is circualting and just open the door once a day?
Thanks..

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Depends on how much "a little" is. Sorry my first post was full of more info than you needed probably. The air in your box should be replaced over the course of every 5 minutes as a rule of thumb, or the plants will be starved of CO2 for photosynthesis. However at night you can probably seal it (night meaning lights off).

Honestly With a soil grow Ph should be a side thought. As you can only ph the water that goes into the plants. If you add some beneficial bacteria to your soil. (great white,zho,myco-grow)(www.fungi.com Recommend) then you wont ever need to worry about your ph. As long as you feed your plants with NON chlorinated water. However Tds meter is a must. (Digital PH is a must for hydro)

As for the temps try to stay between 21-29C. All That Air! A Guide to Proper Ventilation This is a great guide for all your ventilation needs


As for adding Co2 the most cost effective product i can find for providing co2 over a period of time is Exhale Co2 bags. http://www.alternativeco2.com/ExHale-CO2-Bags-p/co2b.htm. This product lasts for up to 6 months and for a little tent like yours should cover all your co2 needs.

Those pills look interesting but it doesnt inform how well they work and you dont have the ability to hang them over the plants so the co2 can draft on the plants (as co2 is heaver than air it sinks to the floor) There are also "the green pads" http://www.thehydrosource.com/Environmental_Controllers_CO2/Co2_Generators/The_Green_Pad_Co2_Generator_5_Pack?zenid=uibvk8l1ucnj9gdbmq1eusgeo6

These are extremely effective all you do is spray with water and they begin emitting co2 but dont last nearly as long

Thanks for replays. I have the heater in the box. The temperatures now with light and at night using heater are just in right range and the intake hole is pretty much sealed up, but not fully, also floor is not insulated so some air gets trough there too, otherwise if i open up the hole, temps would be too low. Closing the hole in the night time would be hard work for everyday(until summer), except if there is any hatch solution i could put on timer?? Well I think i really need some co2 solution then, otherwise plants would suffer as you say or i would be throwing electricity away through the exhaust .. Also the problem is i don't know how to calculate on how much time room's air get exchanged(Without the use of exhaust fan in this cold time) and i have no idea, i just know that the airflow is felt if i put hand where air can get in.... I'm really interested in that exhale co2 bags, but i doubt i can get them in our country.. Well at least if i can order them from europe, i have to check around..

What is tds meter anyway? And about that bacteria thing to add to soil. Do i need one of those or more, as you listed 3 things??

Thanks guys!!

TDS meter measure the PPMs of solids in a liquid. Basically the general idea is that if the parts per million of solids in the water (and eventually the soil) get too high, the plant will not be able to absorb nutrients anymore. Its not my area of expertise, but there are threads that are quite detailed if you search. If its not something you have measured, or even researched, I would go extra light on any nutes, and raise them very slowly if your plants start to show deficiency. I used to use mine to measure my PPM starting point when I used tap water. Now that I use Reverse osmosis water and basically start at 0, I feel more comfortable using reccomended manufacturers doses on ferts.

I honestly didn't use a calculator to measure air circulation myself, I personally just recirculated air as best I could with the equipment I had available, and it probably is actually way more than enough in my case. Since you have special circumstances my reccomendation would be to allow as much air as possible to recirculate, and see how your babies are doing. If they seem to be struggling find a way to get more. "Rules of thumb" tend to have a big grey area anyway so if your plant it growing at a satisfactory rate, leave your set-up as is, at least until you can afford a more permanent solution.

Rush56 said:

Thanks for replays. I have the heater in the box. The temperatures now with light and at night using heater are just in right range and the intake hole is pretty much sealed up, but not fully, also floor is not insulated so some air gets trough there too, otherwise if i open up the hole, temps would be too low. Closing the hole in the night time would be hard work for everyday(until summer), except if there is any hatch solution i could put on timer?? Well I think i really need some co2 solution then, otherwise plants would suffer as you say or i would be throwing electricity away through the exhaust .. Also the problem is i don't know how to calculate on how much time room's air get exchanged(Without the use of exhaust fan in this cold time) and i have no idea, i just know that the airflow is felt if i put hand where air can get in.... I'm really interested in that exhale co2 bags, but i doubt i can get them in our country.. Well at least if i can order them from europe, i have to check around..

What is tds meter anyway? And about that bacteria thing to add to soil. Do i need one of those or more, as you listed 3 things??

Thanks guys!!

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