Please help Guys Need advice coco grow !!

Hey guys started seeing a few problems with my plant. Theres a few yellow scars and the smaller leaves at the bottom are curling up take a look at the pics please let me no what you think. Thanks

Im growing in canna Coco using 40ml of canna A+B in RO water water every 2/3 days ph around 5.8 / 6
Was vegging under t5 grow light just changed to his ( the problem accord under the T5 )
Room temp is about 25c and humidity around 50%
I've got fan blowing on the plant the stems are nice and thick
only got intake fan atm no outtake

Add some cal-mag.

Or epson salts via foilar feed.

What porky said and those look big enough to feed every day now @ around 600-700 ppms. I don't know canna nute's but 40 ml seems awful high if that's per gallon.

How many ppms?

not sure on PPM im useing 40ml canna A+B for every 10 ltr of water