Hi uafgrad, If you mean "TDS 520" with a conversion rate of 500 I'd understand it as rather week nutrient concentration. If on the other hand you are using a /700 conversion rate instrument, your nutrient strength is clearly under 1 mS/cm which is too week. What you most probably have there (according to nutrient strength) is a simple general lack of nutrients that shows up as so called "heavy" marginal and intervenal chlorosis. (magnesium deficiency for instance shows up as intervenal chlorosis and nitrogen deficiency in light green top leafs and yellowing older leafs) Ps: If there is a evident lack in nutrients, there's no "lock-up" needed to get that kind of deficiency signs. You may have a look yourself at this pic: Here is a link that might be useful:

Actually transpiration takes place during Photosynthesis (during light), and photosynthesis triggers the transpiration process. "Although photosynthesis can happen in different ways in different species, some features are always the same. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls." Transpiration is a process similar to evaporation, it's how the plant sucks up the water (and nutrients) from the roots, and eventually evaporates out small pores in the leaves and stems. "Mass flow of liquid water from the roots to the leaves is caused by the decrease in hydrostatic (water) pressure in the upper parts of the plants due to the diffusion of water out of stomata into the atmosphere." "The rate of transpiration is directly related to the degree of stomatal opening, and to the evaporative demand of the atmosphere surrounding the leaf. The amount of water lost by a plant depends on its size, along with surrounding light intensity,[2] temperature, humidity, and wind speed (all of which influence evaporative demand)." And no georgeiii does not have a good point. By that definition (and/or logic) a glass of vinegar has brains when you add a tablespoon of baking soda to it. That has a chemical reaction and therefore would be considers brains. So no, just having a chemical reaction and or electrical impulse is not the definition of having brains. No, the ability to think and reason involves the need for somthing called brain cells (also called gray matter to some people). The ability for a Venus Flytrap to close in on a fly is not a thought it had. It's a reaction to the fly triggering a spring like mechanism in the stem of the plant. The devouring of the fly is just the fly dissolving in a chemical given off by the plant. A plant will continue to grow roots, stems and leaves no mater what, and not just because a root was cut. There is no brain cells involved, and there has never been a plant dissected that has ever been shown to have one single brain cell. Any distinction between so called plant brains and reality is just wishful thinking. As well as probably the result of some deep thought about the meaning of life, and trying to make sense of it. But is simply not based on any actual real science, or reality.

It's not really aeroponics unless you have a high-pressure pump. Probably deep water culture would be the best name. Put the plants in net pots of hydroton, and keep the bottoms wet somehow. You'll want to aerate the solution below. Most people use an air pump and air stone, because it's cheap and easy. I like using a water pump. I'd buy a 30-50gph mag drive pump and plumb it into a pvc manifold. Drill 1/8" holes on the underside of the manifold and your reservoir water will "pee" down into itself. Aeration comes from turning over surface area, and my manifold idea works better than simply spraying water everywhere with cheap misters or fountain pump parts. Ebay sellers call those cheap systems "aeroponics," but without a pump that builds pressure, the particle size of reservoir solution you are able to make is much, much larger. The mist is not nearly as fine as it needs to be to create real aeroponic results. There's more to aeroponics than just roots hanging in air.

Yup. I had an ordinary household compact fluorescent twirly 26W with a built in ballast I paid a dollar or two for when the home improvement store had them on discount courtesy of the G&E, over my tomato seedlings, they grew. For a reflector I used some aluminum foil bent into roughly the desired shape. It seemed I had the foil too close to the bulb, and the base turned brown after some weeks. Got to give it some room, probably would help to have vent holes and fins on the back to help radiate heat. Way less bucks than a HID, but fruiting or even blossoming probably won't happen with tomatoes, but strawberries, well maybe. Lettuce, yes. doodlebee 6, you don't have an ideal situation for hydroponics in your basement. Besides the light, the temperature shouldn't get much under 60F. A couple hundred watts of fluorescents will provide enough light for starting seedlings, if you can keep them warm. Maybe nearer to the furnace, a few feet up, grow short plants? Maybe figure on moving your rig outside come warmer weather and then you have all that sunshine. For a first system I suggest the ebb and flow, with two plastic tote boxes, aquarium pump, water pump, etc. Allows you to regulate how much flood and drain time the plants get. See http://www.jasons-indoor-guide-to-organic-and-hydroponics-gardening.com/homemade-hydroponics.html#flood.