Switching from t12 to t8 fixtures

[Winston]

I am switching from t12 to t8 light fixtures on my orchid cart. Will my orchids which are Phals. Catt, brassavolas be better off now.

[MrHappyRotter]

I made the switch awhile back. It was primarily because I needed to replace some aging fixtures (T12), and the T8s were the same price. They are lower wattage, but put out slightly more (maybe 10%) more light as measured in lumens. I stick with the 6500K bulbs, which is what I used with the T12s.

I grow mostly paphs and phrags. I can't really offer any evidence, certainly nothing scientific, but I definitely feel like the T8s have made a noticeable, positive impact on my plants.

In fact, when I first switched to T8s, I noticed that a number of plants were suddenly showing signs of getting too much light. Some showed "bleached" leaves, general dullness, small/hard leaves, and/or excessive red/purple pigmentation. After moving the plants further from the bulbs, it's been smooth sailing.

I can't speak to the catts and brassavolas, but I imagine they will do better under T8s, if only slightly, and if only due to the slightly higher light output.

Keep an eye on the phals. If the fixtures are the same distance as the T12s were, then you might end up having to move the phals further away form the bulbs.

I am definitely glad I made the switch.

[Ray]

T8's actually put out a lot more lumens/watt.

A T12 is rated at 40 lumens/watt, so a 4', 40W lamp has an initial output of 1600 lumens.

T8's on the other hand, are rated at 90 lumens per watt, so the lower-wattage 32W bulb will put out more on the order of 2880 lumens.

[S&K Maley]

If you have not made the switch I would recommend going to T5HO. We have 7 T8's and recently got our first T5 and the lumens are almost double! When we need to replace the T8 fixtures though we plan on going with a HID 175 watt MH for high light plants and 2 T5's to replace 3 T8"s.
Lighting seems to be one of those topics here which I am sure will get much response.