Complete system

I have a closet that is two by four by 10 feet. I cleaned it out, sheetrocked the four-foot side and sterilized it by washing it with a mild bleach solution. The light is a 250-watt HPS on a pulley system I made from plastic coated wire. All the walls are covered with Mylar.
I built a flood and drain system using a 60-gallon tub and two 14-gallon tubs that fit into it. An air pump and airstones in the reservoir keep the water oxygenated. The water pump is split with a tee that feeds the two grow beds. I placed a plastic coated wire grid in each tray to keep the rockwool slab off the bed floor, to aid in filling and draining. I am going to place four-inch cubes on top of rockwool slabs. I also have an oscillating circulation fan as well as grounded timers and grounded outlets.

What do you think of this room? Do you foresee any problems?

Greeneyes,
Philadelphia, Pennsylvania

You have built a grow room that can be quite productive. The hydroponics system will keep the roots in good condition.

However, you have made no mention of ventilation or odor. Fresh air is needed in your system for two reasons. The first is that the 250-watt lamp will cause some heat build-up in the closet. During flowering, temperatures above 75 deg F (24 deg C) will cause the buds to stretch and grow loose. High temperatures also reduce the yield. Second, the plants will quickly use up the carbon dioxide (CO2) in the air as they photosynthesize. Once the CO2 is depleted, growth will stop until it is replenished.

There are several ways to ventilate your garden. The easiest is to keep the closet door open. A circulation fan will keep the air moving between the closet and the space outside. However, having an “open” system may create odor problems throughout the living space.

Another solution is to build a ventilation system using four-inch flexible tubing with an in-line fan to move the air. The garden air will become more odoriferous each week, so the exiting air should be cleaned using a negative ion generator, ozone generator, activated carbon filter or electrostatic precipitator.

The room next to the closet will also have to be cleaned of odor. Negative ion generators, ozone generators and chemical odor removers can all be used to keep the air in the adjoining rooms odor-free.

Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA. You can also email Ed at [email protected], and send queries via his websites at www.ask-ed.net. All featured questions will be rewarded with a copy of Ed’s new book, Best of Ask Ed: Your Marijuana Questions Answered. Sorry, Ed cannot send personal replies to your questions.

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