Hello all. I have what seems to me (from reading online) to be a magnesium deficiency: There are 2 problems with this self diagnosis. 1. The bottled water I'm using contains added calcium and magnesium 2. The leaves are showing veinal chlorosis rather than the fabled interveinal chlorosis (mentioned on all online sources) which is supposed to be caused by Mg deficiency. As you can see from the pic, it is the veins themselves which are suffering the chlorosis and not the spaces between them. The plants are AK48 and there's 5 of them altogether. The one already pictured shows the chlorosis the best, but another one here is looking much worse for wear: As you can see the cotyledons have yellowed and the lowest 2 leaf sets have brown tips and look a little sad and droopy. Here it is a few days later: Now showing browning tips on the next leaf set up too. Also you will notice the leaf in front looks totally wilted and is collapsing under it's own weight They're in a mixture of compost, peat moss, perlite and vermiculite in little 1 pint pots (I know the pots are a little bit on the small side by conventional standards, but I've seen people have success with such small pots, so I know it can be done). No nutes at all yet. They're a little hungry for light as they're under only 3 23w CFLs for the time being, but that said, spawned just 1.5 weeks prior, a feminised autoflowering roadrunner was given the same conditions and is doing great; The leaves are a nice lush dark green, little buds are starting to form. Granted some of the lower leaf tips have turned brown, but nothing like to the extent seen in the AK48. The only difference is that this plant was fed with an extremely weak solution of nitrogen heavy plant food at about 2 weeks old and then repotted. I checked PH of all plants and it was alarmingly high @ 7.8! I have watered twice with PH 6 water now and it has come down to approximately 7.4. I will continue with this course of action until I reach a more desirable level. I have now repotted 2 of the AK48 (in larger pots) to see what difference it makes. The smaller plant pots are actually water bottles cut in half. They are totally transparent so the roots are exposed to light. I heard from a very experienced grower that light is only a problem in hydro because it encourages algae to grow in the solution, and presents no risk to a plant in soil. Though I wrapped one in foil yesterday to see if it improves the situation. One last little thing... the bottled water I'm using has a starting PPM of 300. I heard that's a little high, can anyone confirm? As I said, it has added Cal and Mag. Thanks so much for taking the time to read this. It'd be killer if someone could lend me some experience in this matter coz I have none.