Observations on a cabinet grow from a noob, 40 days in, 250W CFL, autoflower strains

Hello fellow growboxers !

I'm on day 40 of my first ever grow, here are the setup details :

The GrowBox

Material : untreated, 12mm chipboard.
Height : 3 feet/90 cm
Width : 2 feet/60cm
Depth : 2 feet/90cm
Reflective material : Mylar
Intake fans : 2 x 120mm / 72 CFM (Zalman ZM-F3)
Outtake fans : 2 x 120mm / 72CFM (Zalman ZM-F3)

The Lighting

Brand : Plug and Grow.
Wattage Rating : 250 watts
Actual power use : 193 watts.
Light range : 2,700k Red
Tubes : 8 x 10-inch U-tubes.
Lumens : 19,500
Schedule : 18/6 all the way (autoflowerers), lights on at 11:30pm, lights off at 5:30pm next day.

The Girlies

2 x Lowryder #2
1 x Short Stuff Auto Assassin
1 x Afghan Kush Ryder

The Nutes

Plant Magic biosilicon for early growth.
BioBizz Bloom for flowering.
No vegging nutes as autos don't veg.

The Soil

Peat-free potting compost with vermiculite, perlite and horticultural quartz sand.

Fancy Extras

A small humidifier that outputs 80ml per hour, ultrasonic so low power use and low heat output.
A homemade temperature/humidity sensor/data-logger based on the Arduino Uno R3 (a box of electronic tricks for those who don't know).

The Big Idea

Grow only autoflowering dwarves.
Have a rotation system of four plants, so a 'harvest' of two plants every 5 weeks.

Observations

So, to be clear, this growbox has no extract or intake to the outside of my flat (apartment), so it's a fairly shoddy job, but i rent my flat so i can't start drilling holes in outside walls, etc ...

I'm thinking there are probably many people in a similar situation or thinking about it so it would be good to share some experiences.

Temperature

Having started the grow on April 1st, outside temperatures at night were anywhere from 6 to 9 degrees celsius, during the day they were anywhere from 9 to 11 C.

At first, my lights on temperatures were a little two high, around 32C. This was fixed by doubling the amount of intake and extract fans from one of each to two of each. Now lights-on temps are around 28C and lights off temps around 18C.

Obviously, as the weather gets warmer, lights-on temps will become a problem. Possible solutions include more fans, increase power to the fans, or possibly use Peltier cells to cool down the air :

Thermoelectric effect - Wikipedia, the free encyclopedia

I like to think of electronic solutions, it's always interesting and educational.

Humidity

Damn that water-vapour in the air !

When my lights are off my humidity can go above 70%, with lights on it's around 30%.

I bought a mini, ultrasonic humidifer and that gives me about 45% lights on humidity and i turn it off when lights are off.

To combat the high, lights-off humidity, i have ordered 'Moisture Mate', this is apparently quite efficient.

Odour

Ah the smell, shame we have to mask it :(

My plants only smell a little at the moment, they are yet to flower. The ads say flowering at the fourth week but i think all those figures are for superior lighting systems, CFL's take a while longer.

A homemade filter has to be made for when they start to smell.

My idea is a cube-shaped frame, screwed and sealed to the extract fan hole on the outside of the box, one for each extractor fan.

Each face of the frame has a sheet of activated charcoal filter sealed to it, so you have five faces of a cube soaking up the smell and plenty of space for the air to move.

Well, it's my first grow and i've cut some corners and made a couple of mistakes but it's all been enjoyable and hopefully it will be rewarding in the end ;+}


Cheers,

nibs.