Fluorescent lighting question

[scottn14]

Im looking to build a system similar to the one seen here:
http://kstp.com/article/stories/S3395784.shtml

The issue im running into (and cant seem to find the answer anywhere) is the optimal spacing for a t5 fixture to cover my beds. The beds ive drawn up are 18ftX2ft, how wide of a fixture (number of bulbs and dimension) is optimal for this bed? I can also resize it to better fit a fixture (make it wider).

I keep reading that fluorescents only cover the space directly below them, then other sources say otherwise. The individual in the above video seems to have a bed wider than his light fixture, and he spaces them apart a about a foot as well by the look of it.

How do i know the best way to build my beds / which fixtures to buy to make sure my plants (Primarily lettuce ) will grow well?

[Oliver]

Regarding Urban Organics, they are no longer using T5s. They are now using Inda-Gro Induction lights. Not sure if they have replaced all of the lights but are in the process. The thing that struck me about their operation when I was first introduced to it by the folks at Inda-Gro, was that it was clear to me from my own T5 experience that they didn't have enough light. This can be seen from their Facebook pictures showing a crowning of their growth near the center directly under the lights.

T5s have to be right on top of the plant canopy and cover all of the plants for optimum growing. The bulb spacing of a T5 fixture is set to deliver the right amount of light to the plants only if it is almost touching them. If you raise the light up and try to stretch out the light to cover a larger area, like Urban Organics tried, then you will get the same results they experienced. The tube spacing on the T5s we were using before changing them out for Induction lights was 3 inches between tubes. This should start at the edge of your growing area and extend to the opposite edge with as many T5 tubes as it takes. Going beyond the growing area is advisable in order to cover the outside plants with light coming from both sides. The down side of extending the light beyond the growing area is the added light cost and the energy required.

Oliver

[scottn14]

Very helpful oliver thankyou.
For starting my grow im choosing fluorescents to save on initial costs, when i expand i believe ill switch to indagrow or LED lights.

I will definitely make them height adjustable when i build, thanks.

The only other thing id need clarification on is how far i should space the fixtures apart? Im assuming they should be almost touching eachother as the extend down the bed?

I was considering buying something like this
http://www.ebay.com/itm/Black-T5-HO-4ft ... 1c3eec11e8

So it would likely be proper to buy 4 of these (and possibly one extra 2 ft long one) for my 18 ft bed?
the fixture seems to be almost exactly 2 ft wide so that should be perfect correct?

Again thanks for clarifying the mistakes of Urban Organics, my fault for assuming just because theyre successful that they have the optimal setup.

[David - WI]

Weird, the video is only 3 weeks old according to the caption (4/10/14). They must have either spent a fortune to upgrade all at once or they are just in the process of changing over?

Those High output (T5 HO) seem like overkill for lettuce, but everybody has their own ideas about that I guess. Using a PAR light meter, the regular T5's appeared to put out plenty of light for lettuce and other leafy green vegetables as long as they aren't too far away from the leaves.

We have T5 HO on our citrus trees because the light needs to "reach" further to get to all the leaves on a tree; but are planning on using regular T5 for everything else.

[Oliver]

Scott,

I have sent a PM to you regarding some used lights I have that may be useful to you.

Oliver

[Waterboy2b98]

Take into consideration that you will have to replace the Fluorescent bulbs at least once a year. After I build and paid from my lighting, I was not getting the growth I thought I would. After lots of research, I realized that fluorescent lights lose lighting power over 6 to 8 month period, and need to be replaced to stay at full productive power. Now I have fruiting plants, not just lettuce.
So now LED lights became not so expensive, boxes of bulbs every year add to the operating cost. I just changed out one bank of T-8s for LEDs, and hope to do more over time. Just wish I would have known that before I built!! Just food for thought!

[Roger L.]

They are now making replacement LED builds for most styles of lights from automotive to the normal lamp light. Has anyone seen a LED replacement for the fluorescents?

[David - WI]

They are now making replacement LED builds for most styles of lights from automotive to the normal lamp light. Has anyone seen a LED replacement for the fluorescents?

All sorts of them, but most are $25+ per lamp: http://www.amazon.com/Ledwholesalers.../dp/B002P3FQI6

It uses 35% less energy than a 32 Watt Fluorescent T8, but provides the same light output.

http://www.warehouse-lighting.com/4-...FYlFMgodeEEAGQ