new grower, yellow leaf tips. can anyone help?

Im a first time grower and my plants seem to be having a problem. my plants are about 15 days old and it started like 5 days ago. it started at the bottom single bladed leaves, and seems to be working its way up. well the tips first turned brown, then the leaf starts turning yellow around the brown spot. and on the single bladed leaves it turned about half the leaves brown so i just cut them off. the next set ( 3 blades ) is starting to have the same problem. i have 3 plants and they all seem to have the same problem, but it shows more on my biggest plant. the single bladed leaves on my 2nd biggest plant has brown tips and is kinda starting to yellow. i thought it could be a magnesium deficiency so i foliar fed them with some epsom salt diluted in water but its been 2 days and the problem still seems to be there. another thing i should mention is that there is still new growth, about every 3-4 days a new set of leaves appears to be coming out. some other things i think i should mention are that i dont know the pH of my soil and i am growin them under a 75W Flo, i know its not very good but it'll have to do while i get a HPS. i will attach some pictures and hopefully someone can help me.

What growing medium r u using, if u have been putting to many nutes in, u should'nt have put any nutes in for the first 2 weeks at lest then even slowly raised the level of the nutes to youre MAX.And if u r not to sure about the PH level in the soil just flush the plants with PH-water.:).

GOOD LUCK:)

PS WHAT STRAIN R THEY???

PEACE TO ALL:).

I agree, feed em plain water for a week, then give half your fert solution to start with, sounds like you're overloading them with fert too early in their lil' lives.

well when i thought that might be the problem, i flushed them one time, and the only nute gave them after that was when i foliar fed them with some magnesium. they seem to be getting better. there is new green growth at the top the only thing that looks wrong with them is the old leaves that were already turning yellow. but once the plant begins to have new growth, the tips on the old leaves begins to turn yellow. but as of now its only the tips, it hasnt spread throughout the leaf or anything. i have transplanted them once from one of those little 5" cups to a bigger cup about one foot deep and 5" in diameter. when i did this i had 4 little plants, but one died. so i now only have 3. i think someone also said it might be because the soils bad so i wanted to go buy some new soil and plant them in like a 3-5 gallon pot so i wouldnt have to transplant them ever again but im afraid of losing any more of my babies, since they dont seem to be in perfect conditions. another thing, one of the plants seems to be concentrating more on stem growth, its about 5-6" tall and only has 3 sets of leaves and there is about 2 and half inches of space between the first set and the second set. about the strains, i dunno what kind they are but i think one might be sativa and one might be indica. i dont know if you can tell now that they are still little. i just planted some flame that i came accross. but one plant has smaller leaves that are more closely together, and the other one has leaves like twice the size that are spread out more, and the one with the smaller leaves is working on its 5th set of leaves and the one with the bigger leaves has its 4th set out just not full size and you can also see the 5th set on its way out. lemme know what u think about transplanting them again. also, i have this pillar type of thing thats about 2 and a half feet deep that is hollow, so i broke the bottom and turned it upside down and put the plants in there, then i cut out this thick carton square and put a hole in the middle, stuck a lamp through it and lined up the walls with aluminum, dull side out. i did this because last time i tried to grow my parents found out when my babies were like 5 days old, so they got rid of em. so now if they ever come in my room i cover up the opening with the carton square so u cant see in there or light wont come out. i also have this tiny fan in there to circulate the air that is powered by 3 AA batteries. i want to put a bigger fan to encourage stem strenth but i have none that'll fit in there.

just lettin ya guys know, i moved my plants from that 1 foot deep cup to a 3 gallon bucket. i have all three of my plants in there, i know you should allow that for only one plant, but more than likely not all three will be female, if any. i took some potting soil from this plant my mom had, and replaced it with some dirt that was in a pot. she bought the soil at the store but hopefully it had no bugs, cuz that would REALLY suck. this new soil is so much better, the other one would clump together like mud and when it would dry, it would get real dry and crack. this soil is black in color, soft and doesnt clump. i transplanted the 2 bigger ones with the old soil but the other one i only transplanted it with the root ball. am i doing good or bad so far? all your help would be greatly appreciated.

Sounds like you're on the right path. THe old soil sounds shitty and it's a good thing you got rid of it entirely. Now you just need to let them recoup from all the moving around. Hopefully you should see some improvement, at least in your new growth, within a few days, good luck!