Started my system around January of this year, it cycled around March.
The system is in the basement which I imagine stays around 60 - 70 degrees.
I am using hydroton for the grow medium, I am currently using some LED lights but I have also used a T5.
The plants come up very quick, lettuce takes a day or two and grows fast and looks pretty good, then when it gets to maybe three inches or so they start falling over and go down hill from there.
They are not wilting or dying before they fall over, Its almost like they are growing to fast and don't develop big enough stems to support themselves.
I really do not understand why this is happening, the only thing I have had some success with is basil some of them will stay upright and do well others just fall over.
I use lettuce as an example because you would think that this would be fairly easy to grow.
Sounds like a light problem. How close to you have the lights from the plants?
i agree. I keep my T5's about 2 inches away from the top of the plants. I also use a small oscillating fan that's on the timer with the pump.
Thank you for the tips on the height of the lights, I had them probably 2' above.
I will try lowering them to 2 inches above.
How old are those T-5 tubes? You need to change out all fluorescent tubes after about 6 months. Even though, to your human eyes, they still look the same as the day that you bought them...PAR (Photosynthetically Active Radiation) starts to drastically fall off and plants start to suffer...so they need to be changed out regularly. What you described sounds like plant 'stretch', which is usually indicative of their not being enough usable light.
The tubes are still good for "human" purposes (lighting a room/office etc...) so you can use them elsewhere in the house or donate them, but are pretty useless for growing plants once PAR begins to decrease. I don't know if the people you bought them from let you know, but this having to change out tubes twice a year or so is standard operating procedure when using fluorescent lighting.
I just re-read this post...and what Nat says is true. In addition to giving the plants the hoola-hoop treatment (strengthening stems) a fan also helps with fungal/transpiration issues but anyways...the thing that came to mind when I re-read your post (other than sucky LED's) was...Carefully and gently extract and and examine one of your fallen over plants. Pay close attention to the crown (which is the area where the stem meets the roots). I'm betting that you might see that a very small (couple of millimeters in length) portion of the crown/stem has "thinned out" and can no longer support the portion of plant above it, and that's why they flop over...This is actually quite common in indoor hydropnic/bio-ponic growing...It's caused by an oomycete, generally because things are too moist at the seedling stage. Stagnant air just exacerbates the problem. So does having weak seedling (like not enough light etc...) This also happens in "regular" gardening if seeds/seedling are kept too moist when little.
I concur with Nat and Vlad. The use of a decent fan will get your plant stems lookin' nice and strong.