I’ve never grown with T8. As you’ve said, the common information is that they aren’t suitable for growing. Have you tried T5HO or those Cree LED "lightbulbs" from Home Depot? (<<link) I’ve used both and they’re great. It would be interesting to hear how T8 compares to those alternatives.
me and.my woman put away about an oz every 2 weeks lol
For flowering, you really want HPS, or if you’re rich, LED COBs
Second, T5 bulbs tend to produce more heat than T8 bulbs. If you’re looking for a lighting solution for a closet setup without ventilation, this heat could lead to unsuitable growing conditions at any stage.
Because the T8s give off less heat and less light, they are in fact more suitable for these early phases. If you were to use a brighter, hotter T5, you would run the risk of scorching the plants or upsetting their biological rhythm necessary for the early stages of growth.
T8 Grow Lights Explained
Once your plants are set up to thrive past their initial growth, you really need the higher brightness capacity of T5 to grow lights. As photosynthesis really starts to ramp up during these growth phases, the more light you can provide to your plants, the better your final outcome – and heavier your harvest!
The most common of all T style bulbs, T8 grow lights are a tubular style of lighting with a diameter of 1 inch.
When it comes time for the vegetative and flowering phases: The T5s are your best bet
If your setup is prone to overheating due to lack of appropriate ventilation, being in a difficult growing climate, or growing during the peak summer season, T8s may be a better choice for you during the cloning, seeding, and rooting phases. Here, they will provide sufficient lighting for germination and deep rooting without running the risk of scorching or drying immature plants.
Now, what about the "grow" bulbs they offer in this size. I have not looked into it so I am not sure if the "grow" bulbs put off more light or if they are just a different spectrum.
Maybe I can add some ventilation to the closet. What might be nice is a 4 bulb setup with a switch to use 2 or 4 bulbs.
Just for the purpose of upgrading, I was thinking about a T5 fixture.
T12 = 2650 initial lumens (they drop off the quickest of all) for 40 watts.
T8 = 2800 initial lumens, (they hold their lumens much longer than T12s) for 34 watts.
T5 = 2900 initial lumens, (they hold longer than T5s) for 28 watts.
The grow tubes lean toward the red spectrum. More for flowering than anything else. The cheap blue ones work fine for veg/seed popping.
Would a 2 bulb 4 foot be enough (at least equal to the 2 shop lights)?
I will have to check on that. If the lumens are the same and the spectrum is more in the blue, that might be a good thing, yes?
I did use this closet for early vegging for years but now that I have the tent, this closet is just for cloning and popping seeds.
I’ll keep my shop lights. They are my old friends, anyway. LOL