Can someone please help identify what's wrong with my tomatoes? Please help! (Picture attached)

[bhaugh]

The reason is that plants don't photosynthesize correctly for growth under red lights and start showing signs of deficiency, turning the plants a purplish red color.
Young plants need a blue light spectrum to photosynthesize correctly and keep that nice dark green color.

If the grow light is good, this shouldn’t be an issue. Grow lights have come a long way and integrate both blue and red in one unit. People may pooh pah the cannabis industry, but their desire to succeed in their industry has pushed grow light producers to make a better product. Although I use Spider Farmer grow lights and like them, their CS is terrible and has made me look for alternatives. When buying grow lights don’t skimp because of price. Buy the best you can afford.

 

[Chris2018]

If the grow light is good, this shouldn’t be an issue. Grow lights have come a long way and integrate both blue and red in one unit. People may pooh pah the cannabis industry, but their desire to succeed in their industry has pushed grow light producers to make a better product. Although I use Spider Farmer grow lights and like them, their CS is terrible and has made me look for alternatives. When buying grow lights don’t skimp because of price. Buy the best you can afford.

It doesn't matter if the lights are good or not, young and growing plants don't use that much light in the red spectrum. Under a red spectrum seedlings and young growing vegetables tend to be more lanky, less bushy, show some signs of deficiencies and show signs of stress do to incorrectly photosynthesizing.

Yes, the cannabis industry pushed the agriculture companies to make better products.
In doing so we got much better lighting, soils, organic fertilizers etc. BUT like in the case of lighting it doesn't change the fact that young and growing don't need a red or "full spectrum" light.

 

[SmiYa0126]

What I see is phosphorus deficiency but I think your lights are too close also

I agree, this is a phosphorus dificiency

 

[The_Chicken_Tender]

It doesn't matter if the lights are good or not, young and growing plants don't use that much light in the red spectrum. Under a red spectrum seedlings and young growing vegetables tend to be more lanky, less bushy, show some signs of deficiencies and show signs of stress do to incorrectly photosynthesizing.

Yes, the cannabis industry pushed the agriculture companies to make better products.
In doing so we got much better lighting, soils, organic fertilizers etc. BUT like in the case of lighting it doesn't change the fact that young and growing don't need a red or "full spectrum" light.

So do you believe it is better to have a light meant for seedlings specifically, rather than full spectrum?

 

[The_Chicken_Tender]

Thank you everyone for the help. After fertilizing, the plants seemed to continue to get worse for a while, but now the new growth actually looks very healthy. I did move the plants under a different light that wasn't so close, so that may have also contributed.
Some other tomatoes seem to have some problems (they aren't turning purple - they are shriveling and curling for some reason) and that may be a disease, but the problem with the purple tomatoes does seem to be at least partially caused by a nutrient deficiency.

 

[Chris2018]

So do you believe it is better to have a light meant for seedlings specifically, rather than full spectrum?

IF, you are just starting seed and growing young plants there is no real reason for a full spectrum light and it is better to have a light/s that are in the correct spectrum for seedlings and young plants.

If you're going to buy a full spectrum light, I would buy one that allows you to switch between blue and red spectrum.