Need Advice With Indoor Grow Box

Discussion in 'Growing Marijuana Indoors' started by Zondagh, May 27, 2013.

  1. Hi Guys
    I have started my first grow box. I have read much and I have made many mistakes and I have learnt a lot. I now need some more advice.
    Basically, I have a wooden frame built that measure 1m x 1m (3x3) and its stand 2.4m tall. Its sides are closed with 3mm super wood boards. The outside is sealed with white plastic sheeting and the inside is completely covered with mylar. The door is a piece of sisalation that I glued and stapled to the top of the box and that gets sealed to the front of the wooden box with velcro.
    Inside I have 7 (should have been 9 but two died) square white pots, 25 litre (5 gallon) each, each with a feminized Ice plant in them from Royal Seed Company. My soil is a mixture of peat moss, perlite, building sand and compost which contains mostly worm castings and manure, and some bonemeal. Each pot stands on four bricks, which has a gutter underneath them which are removable for drainage. The pots have several holes at the bottom the size of a medium thickness marker each. The pH of the soil is between 6.5 and 6.9 and seems to retain moisture sufficiently.
    I have a 400W Sunmaster MH lamp in a birdwing reflector which is run by a 400w adjustable electronic ballast, which is on a timer with four hours dark time (veg stage) in the middle of the day. I also have an Osram Plantastar HPS for flowering. 
    I have two inlet fans at the level of the tops of the pots which are 16W each which moves 160m³
     of air per hour. At the top of the box I have a 22W in line duct fan which moves 190m³
     of air per hour. There is a duct which stretches from the reflector, to the top of the box, over the in line duct fan, then exits the box and carries on about a meter and a half (4.5 feet) to a window which has a window duct fan installed in it, with the same specs as the one on the box, which is my exhaust system. There is also a 6" oscillating fan inside the box which blows over the plants.
    So the box is standing in a room, and it draws air in from the room, and then exhausts it through the duct outside the window. The room is an old store room about 3mx3m (9x9 foot) with a tile roof which is not insulated much. There are enough open spaces all over the room to draw in enough fresh air for the inlet fans to go into the box. 
    I also have an emergency fluorescent lamp inside the box which goes on during a power outing during the light stage to prevent the plants from being exposed to irregular light schedules, because power outages happen quite often where I stay. These lamps can run for 6 hours on a built in battery and is enough to keep the plant 'awake', even though they wont grow much under them. 
    The idea is to top each plant twice (soon) and then start to train all seven of the plants to fill a screen of green. As soon as the screen is filled, flowering can begin. I plan to put up the screen about 20-30cm above my pots, which leaves me with more than 3 feet for flowering.
    I have found that I have some serious humidity and temperature problems. My lamp is about 40cm from the plants. The temperature reading at the level of the plants is 26 degrees Celsius (79 Fahrenheit) and the humidity ranges between 40% and 50%. At a higher level, above the light, the humidity is between 50% and 60% and the temperature is at about 22/23 degrees Celsius (71-73 Fahrenheit). Also, these readings are when I leave the bottom of my door open so that more air can enter the box. When I seal the box completely, the temp goes up to 29 degrees (!!) (84 Fahrenheit) and the humidity drops even a little more, nearing the 40%'s. 
    The top layer of soil in each pot dries out quite quickly. A moisture reader tells me that the soil below is still moist. So I take it the soil is holding moisture sufficiently but the top soil is drying out too fast. 
    Also, it is winter where I am, and conditions are pretty cold and wet. The temperature in the room is almost always about 3 degrees Celsius warmer than outside, which goes to down about 7 degrees Celsius (44.5 Fahrenheit) at night and peaks at about 19 (66 Fahrenheit) degrees in the daytime on a warm day. Therefore my lights are off during the middle of the day so that the plants aren't exposed to too low temperatures during the dark phase. Lately, temperatures have dropped even below 15 degrees Celsius in the day which makes me think I will soon have to run a heater inside the room on a timer which switches on during the dark phase. That will also in turn lower the humidity even more.
    When the lights are off, the humidity rises to between 60 and 70, which is more or less similar to the humidity inside the room, which is slightly lower that the outside humidity. When it rains the humidity in the room can reach 90% and higher, but with the lights on in the grow box, the humidity stays low, between 50 and 60%, if not below 50%.
    I have read up on the strain characteristics of Ice. There's not a lot of info on it (or I may just not be finding it) but I did find a site that says the plant prefers warmer temperatures but also higher humidity. 
    So, with my slightly higher than optimal temperature, I shouldn't have a problem with this strain but my humidity is too low. 
    The plants seem to grow fine, yet some are growing faster than others for reasons I cannot explain. 
    What I foresee is that both the temperature and the humidity will rise as the plants get bigger and enter the flowering stage. Since the humidity is way low now, this will be beneficial during flowering. Also, when summer comes, that room is going to be hot and the grow box will be way too hot to grow anything in it the way it is going now. 
    I suspect the reason I have such high temperatures and low humidities and such a huge fluctuation between dark and light phase, is because of the bird wing reflector. Maybe this is not the ideal reflector for a grow box of this size. I did look into getting one of those hoods which are sealed with tempered glass with an inlet and outlet hole for a duct system to attach to which should cool the light and prevent excessive heat from reaching the plants. Then I will get another in line duct fan which i will mount on the outside of the box to suck in air from the room, through the hood, and then out the same way it is currently set up, through the two duct fans and the 4.5 foot duct out the window. Then I will take one of my existing inlet fans inside the box, move it higher up in the box and make it an outlet fan instead. That way the box will have its own circulation via the two 16W fans with an airflow of 160m³ per hour and the lamp will have its own circulation at 190m³ per hour.
    What do you guys think? How much more effective are one of those sealed reflector hoods in maintaining temperature and humidity? Or should I just pop a humidifier/air-con in the room? Maybe when the plants are in flowering and I find the humidity is a problem, then I can change to the bird wing again?
    Any advice and more information on the Ice strain will be appreciated.
    I will post photos soon.

  2. #2 GanjFarmer', May 27, 2013
    Last edited by a moderator: May 27, 2013
    God that was a lot to read lol. To fix the temps easiest thing to do is get a higher rated cfm exhaust fan honestly. Although your temps really aren't horrible, I mean it's not like they're in the high 90's or anything. And for humidity, I've heard putting a large bucket of water in the room helps due to evaporation. 
  3. Any store bigger then a mini mart should carry something like a Vick's humidifier, the kind you use when sick. If humidity is too low and you can spend like $20 to help get you 7 plants through to harvest it'll be worth it's weight in gold.
  4. Thanks GanjFarmer. Yeah I left a lot out. I can get quite technical. 
    I did actually place a few buckets of water in the room with a towel hanging in each one kinda like a wick. It seemed to have increased the humidity inside the room, but the box remains low.
    As for the fans, I understand it so yes, that a bigger in line fan and duct will solve the problem of the temperature but with how much really. And when summer comes again, will it be enough or did i waste my time and money in the end. Would a sealed reflector hood not maybe be a more effective solution in the long run?
    I am sure the two inlet fans can provide enough circulation for the plants if I turn one around and place it at the top, and I'm also quite convinced in my own mind that running a duct system through one of these sealed reflector hoods with an airflow of 190m³ will be enough to cool the light sufficiently. My duct and fans are 120mm, so thats 4.7 inches, and the hoods inlets are 6", but that should not be a problem, airflow will still run at 190m³ which is more than enough. 
  5. Thanks Jmosley
    I did consider one of these too. They go for about $12 around here. Which is much less than $250 dollars for that reflector hood. Where I stay everything is imported and overpriced.
  6. If dealing with low humidity, I'm not sure why anyone in a 4x8' tent or smaller would need more then a cheap one.

    But after re-reading your post, even with you sealing the bottom bit and it reaching 84 degrees... I don't see that as a deal breaker and 40-50% humidity during veg seems pretty spot on too so if I may say so, you might be stressing over nothing.
  7. Do you have any reg. house fans in there pushing around air? I only see mention of intake and exhaust fans. But well geting a better fan now will solve this problem and summer if you get the right one. How I see it is, if the room is too cold becuase the fan is too much, you can use a small space heater and problem solved. But for cooling it down, that's a little harder. So I find it easier to get a really good fan and if temps are to low then fix it, way easier than trying to cool it down.
  8. Ok that makes sense thanks. I do have a small element heater I can use. 
    And yes I have a 6" oscillating fan on the inside blowing over my plants. I plan on installing another one as the plants get bigger.
    Also keep in mind in summer when i say it gets hot it gets really hot. Outside temps can easily go above 38 degrees Celsius and that room is even hotter inside because there's no insulation and it bakes like an oven.
    'Tis Africa baby....
  9. As i understand it you want a humidity of 60 to 70 during veg. And 50 to 60 during flower or even lower. I know the low humidity wont be harmful during the veg stage but it isnt preferred according the strain guide on Ice. Even though i am unsure how much of an impact this will have, i tend to be a bit perfectionistic. Right now its standing at 50.

    I dont like the fact that the top soil dries so fast. It means i have to water more regularly and smaller amounts. I'm using a spray bottle at the moment so that i dont water them too much but i evenly wet the top soil. Im afraid the roots might dry out too much as the plants arent rooted very deeply yet.

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