Fluorescent light question T12 vs T5

I have been using 4ft 2 bulb fixtures over my flasks and am starting to try some T5 fixtures. The T12 are 40 watt and the T5 are 54 watt. I am a bit vague on all of this, but my understanding is that T5 put out more light per watt than T12. Does anyone have any experience with converting? Could I get by with only 1 bulb T5 replacing 2 bulb T12?

 

I appreciate the input. I have been buying fixtures from the hydroponic industry that accept T12 and T8. I had a lot of T12 that I had been given and was using them up. The first batch of T8 that I tried in them didn't seem to work, but it turned out to be that particular fixture. I have just purchased a couple of T5 fixtures to try since I am out of shelf space and lights again (already).

I"ve been trying to find where I put my light meter, but it hasn't turned up. Thanks to Jon too.

I take back what I said about the T8 not working in the fixtures, they only work for a few minutes and then stop. At least I can return most of them.

 

Thanks, Kyle. What is the width of your shelf? Mine are 2 ft wide. Are your shelves grate or a solid material? And how many hours a day are your lights on?

 

Kyle, thanks for the info. And thanks for the image of your lab set up.
Ray, that is really good to know. Even with the 2 fixture T12, I see some of the seedlings on the outside leaning to the light as they get up in size. I have been considering using two foot tubes going across the shelf and spaced at 1 ft and 3 ft (approximately). I bought one of the reflectors for a T5, but it seems very pricey for what it is. I have some heavy mylar that I am going to put under the shelves (above the lights) and on any sides where I don't need easy access.

 

Thanks for asking them. I've been told the same thing at Home Depot, but the light fixture box clearly states that it can be used for T12 AND T8. It specifies the correct bulb ID to use for each of them. Clearly, it isn't working for me. I'm not sure that the company is going to take back all that I have purchased in the last year, but certainly most of them will go back. At least 12 fixtures will be returned.

 

Thanks again, Ray. Both the T12/T8 and the new T5's are from Hydrofarm. I'll play around with this a bit. I'll certainly add the reflectors if I can get away with less fixtures and less bulbs. I'm impressed, I doubt that my tests will get as far as graph form.

 

If you could grow flasks in the dark, tissue culture labs would be saving money by not having lights. Most everyone (who isn't selling lights) has told me don't bother with grow lights since I'm not trying to bloom them. But no one has told me not to bother with lights. I have been told that if I want to keep mothers from progressing I should put them in a darker spot. I have had some overgrown mothers in petri dishes stacked three high and the plantlets in the two lower ones are leaning horizontally to the sides where there is a bit of light.

 

I guess I misunderstood what you were saying.

 

I am part way through replacing my 4ft T12/T8 fixtures with new 4ft T5 fixtures with reflector. You were right Ray, the reflectors make a big difference. Also, the new fixtures are a much lower profile so I am going to be able to have less distance between the shelves and still be the same distance from the plants. I am not happy about having to reconfigure the shelves since I just did that over the last 6 months, but will be worth it in the end. I'll post pictures when get done, hopefully next week.

 

Here is a picture of the current lighting for my flasks. It is a pleasure to work in the room. I love the T5 fixtures. There is NO buzzing or humming, one 57 watt bulb easily replaces to 40 watt T12. I would highly recommend the extra expense if you are considering purchasing fixtures.