Slight lightburn?

Hey! It does look like your plants might be getting a bit too much light, especially if the leaves are starting to lighten and pray upwards. You could try dimming the light a little or raising it to around 50-55 cm to see if that helps. Sometimes young plants are more sensitive, so a bit of distance can reduce stress. Keep an eye on the leaves over the next day or two – if they stop yellowing and relax a bit, you'll know it's helping.

*raise dose of fertilizer not "raise your does" -- type-o

I think your light is fine now, but you can see those first 2 nodes of growth are quite tight (i'd wager the plant was just a bit young when it occured and was receive a bit too much at that time). You were probably giving it a bit too much light when they developed. the node spacing after that looks healthy. Make sure the space between nodes does not get too lanky or too tight, and your light levels are probably fine by doing so. Grow lights make plants look pale. you can see this in my recent diary if you care. I took some pictures at 'full' power for vege and then a few pictures with the light turned down as low as possible. They look almost sickly under full power but are a perfectly normal green with normal lighting. Your plants may not be as pale as you perceive them to be. if they are still pale in normal lighting, raise your does 5-10% and see how that goes. with small plants you can get creative with hanging distances and power while focusing on a smaller area to conserve electricty. This takes trial and error to map it out if you choose to do that. Most lights cover their core area well from 18-20". If you grow photoperiods you work out best coverage for the 12/12 cycle which requires the most power. From there you run it at 2/3rds power in vege -- assuming 12h and 18h operation. It is proportional to hours of operation. QBs should probably be a bit higher at times and LED frames that spread the diodes out more can be a bit closer. I have bar/strip framed lights and 18" is about perfect. YMMV. I only adjust power relative to hours of operation and don't fiddle with it otherwise. I do have a reduced hanging distance and power in early vege to save some watts, but that is a matter of doing it to map it out.

I see no praying here. Your leaves are flat. Plus plants are pale, either wrong feeding or ph and that influence uptake.