Light coloured growth and purplish stems

There is nothing wrong with them. Do you check your PH ?

They are actually good. At the begninnin they never get the intense green. I advise anyway a spray of algae and fulvic acid. If you are following the schedule, the problem could be pH too. Anyway I wouldn't be too much concerned

The stressmark-spots could indicate ph fluctuations, as they result from bad nutrient intake. The overall light greenish tone and purple stems could result from low Mg levels. If adjusting ph isn't enough any CalMag nutrients will do.

They might be a touch pale but looks healthy. Really it's better to under do it than to go overboard when it comes to nutes, especially when they're still pretty young. I'd hold course until they got a little bigger unless they get paler. Once you've got 3-5 nodes the plant can handle a lot more stress.

They look like they need some food to me. Hard to say when every camera has a different exposure, but to me they look anemic and are in need of nutrients. 250ppm of a balanced growth stage nutrient feed and they will perk up and turn a lovely green

Purplish stems can be a magnesium deficiency. They look pretty healthy though.