[GpsFrontier]

Hello Davephan,
This reply will be in two parts because it's to long to all fit in one post.

1.) Can the grow lights be run 24 x 7 to increase production, or do plants need to rest from the light? Are there diminishing returns running the lighting 24 hours a day verses about 12 to 16 hours a day?

While there is some study's that suggest that plants benefit from a period of darkness, I think the study's are somewhat subjective rather than conclusive. Especially since not every crop/plant is the same, and I would point out that the largest produce grown comes from the Matanuska-Susitna Valley in Alaska (also known as the land of the midnight sun) where they get more hours of sun than anywhere else. And during summer months the sun never goes completely down.

2.) If the lighting is run 24 x 7, should the watering in a non-static system also be cycled 24 x 7?

This depends on the hydroponic system. While plants roots need access to water during light hours when they conduct Photosynthesis, not all hydroponic systems need the water circulating constantly during light periods. How much the pump needs to run depends on the type of hydroponic system, how it's designed, the type of growing media, etc. etc..

3.) Roots need to be in the dark. I assume in as close to total darkness as possible. The hydroponic growing channels seem to always be constructed with white colored plastic. If black plastic was used, inside the channel would probably be darker. However, outside the channel, the black color would absorb more light instead of reflecting light in the growing area. Does the white colored plastic provide a dark enough environment for the roots, while allowing more reflecting light in the growing area?

Yes, the roots should be in total darkness. Light in the root zone will allow unwanted microorganisms and micro flora to grow, and if the light is strong enough can also damage the roots. While white plastic isn't always completely light proof, the type and density make a big difference in how much light gets through.

It's not hard to light proof the root zone no mater what color the plastic is, and/or how much light gets through it. I used to paint it black to block light, then a few coats of white to reflect light, and this does work well as long as you sand the plastic so the paint sticks well. Paint wont last years on smooth plastic, so scuffing it up with sandpaper first gives it a good surface to stick to.

But I don't really do that much any more. Where I live here in the desert I often need to insulate the root zone also. The insulation itself acts as a light barrier. I also find it easy to laminate panda plastic on any plastic. Panda plastic is black on one side and white on the other. Just cut the plastic to size, then spray some spray adhesive on both, then wrap with the panda plastic. When I want rows of tubes, I usually use ADS (Advanced Drainage Systems) tubing, it's white on the outside, and black on the inside. For the water feed lines I mostly use black vinyl and irrigation tubing, if it's going to be in the sun, I cover it with pipe insulation.

4.) led grow lights might be the best lighting solution, since the heat problems are eliminated and the energy consumption is drastically reduced.

That is really mostly manufactures propaganda to sell products. But the fact is there is no creditable study's that have been done to substantiate those claims. Not that I have seen yet anyway. The study's that manufactures refer to were done by the manufactures themselves. And they purposely omit anything that doesn't sell products. There is basis for both claims, but when put into actual practice it's not what it seems.

First, yes the LED bulbs are much cooler than a HID bulb, but the wattage used by LED's is generated by the circuitry, not the bulb itself. A 40 watt LED light fixture is going to generate 40 watts of heat, it's just that the heat isn't radiating from the bulbs, so the bulbs are cool to the touch. But the fixture itself still has 40 watts of heat to get rid of.

Second, the actual amount of wattage needed to grow your plants with LED's will be almost the same as with HID lighting. Energy costs are based on wattage. So if your using the same amount of wattage using LED's, there is no energy savings. Manufactures base their claims on the wattage of their LED light fixtures, not on what it takes to grow a particular plant. In other words if you need ten 40 watt LED light fixtures to grow one tomato plant, that's the same wattage as a 400 watt HID light. Thus the same energy consumption and energy cost. Despite what manufactures want you to think, just because a particular LED light fixture uses less wattage doesn't make it equal or comparable in growing your plants. But with the right LED light fixtures and spaced correctly, it is possible to lower energy costs 10% to 20%, but nowhere near the point that the LED manufactures and retailers want you to believe.

5.) Is the main negative against LED the higher cost, compared to using HID or hps lighting?

Yes.. With the high equipment costs and multiple LED fixtures needed, along with low returns on energy savings, it would typically take about 10 years to to just break even. That is take 10 years to save the same amount of money in electrical costs, to make up for the higher initial equipment costs.

6.) There are many types of LED lighting. Some systems are priced below $100 and others are $1,000 and more. Are the less expensive LED lighting a good compromise instead of purchasing the expensive LED lighting? Is there a point of diminishing returns that is beyond the less expensive LED lighting?

Good LED row lights will be expensive. However with lighting manufactures realizing the growing market for LED grow lights, and wanting to get a piece of the pie, the market being folded with inexpensive low quality lights. As well as high priced low quality lights (especially from china). So you have to do your research, not only on the particular light fixture and the circuitry and bulb specifications, but the manufacture of the lLED light fixture as well.

7.) When growing plants inside in a controlled environment, can plants produce crops continuously for years, do they go through cycles, or do they taper off production over time?

It depends on the type of plant, all of the above. Some plants will die off after they produce. Some plants typically die because of weather, but can survive for another season. Some plants die off and naturally come back the next year. Typically called overwintering. While tomato plants are generally regarded as seasonal plants, they can last and produce for years. The tomato tree in Epcot center is a perfect example. That's not saying the plant will produce non stop, but will over winter, and will come back the next year.


If you want a non stop year long supply, you'll want to rotate plants. As an example: if you want to have 2 tomato plants of a continuous supply of tomato's. You should design a hydroponic system that will grow 6 plants simultaneously. 2 new plants, 2 four month old plants, and 2 eight month old plants. This way every 4 months you can rotate the old plants out, and replace them with new plants. This way you will have a constant supply of tomato's, and new plants growing tomato's that will be ready to harvest in the future when it's time to pull the old plants out. You would start the new plants a few weeks ahead of time in a prorogation system so they are big enough to transplant into the main system when it's time to rotate the old ones out.

8.) What is the ideal liquid temperature range?

68 to 72-75 degrees Fahrenheit. I wrote this article about nutrient solution temperature: Nutrient Solution Temperature is Important

9.) How important is accurately measuring PH?

pH is very important, but the term "accurately measuring" is subjective. If by accurately measuring you mean a reliable method, very important. If by accurately measuring you mean how often, that depends on your experience. I would say you should check the pH every day or two when you first start growing. Then as you learn how pH fluctuates and why, and can practically guess what the pH will be before you check it, then you don't need to check it as often. If by accurately measuring you mean down to the percentage point like 5.9 or 6.4 verse a pH range like between 5.5 and 6.5, not important at all. All you are looking for and needing is to be within a specific range, not at a specific percentage point.