I'm going to move this to problems, since you DO have a problem.
That plant is showing classic but mild Mg deficiency. You need to identify the cause, but in the meantime, dissolve 1/2 teaspoon of Epsom salts in a gallon of tepid water and mist the plant lightly with that. Only do this a couple times.

Be sure that your soil pH is 6.5-6.9 and your soil is free-draining and not sitting on a cold surface.

That plant is old enough to start feeding a weak solution of a complete grow fert. The first week, only feed at 1/4-1/2 the recommended strength.
stinkyattic Reviewed by stinkyattic on . Does this look OK (Pale Veins) Hi Guys, Just need a liitle advice on my Great White Sharks. On day 14 and have noticed the paler veins on the leafs, is this OK. Their in John Innes No3 from seed under a 400W MH running 20/4. Only my second grow and as my first all turned Hermie on me (Dutch Passion Skunk11) I want this grow to be better. Thanks in advance Bazza Rating: 5