A little plant trouble, help please!!

Ok, i'll basically show the set up I have. I actually didn't record when I first set everything. I initially had the 3 big one's first; they are regular bag seeds. The 4 small one's are actually Hindu Kush and Sour Diesel. I wanna say I started the growth of the small one's back in the 3 week of December; they were on 18/6. Now I started flowering and this is what's happening to the leave's; they are turning yellow at the bottom tips, any help would be great. Also, the plants are at a friends house and he is not always home,, he waters once in the morning and sometimes he doesn't get home till late sometimes. . .im thinking thats the problem. I try going like everyday now to make sure they are being watered properly. I don't use a PH tester or anything of that sort, just regular sink water. Other than that i'll keep you guys posted with pics.

I'll start by saying that this thread is super helpful for diagnosing plant problems.

The little ones look to be slightly overwatered. It could just be the water that is on the leaves causing them to bend down but I really don't know why you would be spraying the leaves anyways.

For the larger ones it would be helpful to know what kind of soil and nutrients you are using. Also, a ph test kit at a local hardware store should be really cheap. So even if you don't want to drop $60-$150 on a decent-good meter you can still check your ph and eliminate that as a problem.

Have you been giving them any Nutes yet? And a couple of those bigger pots barely have any soil in them, its gonna be hard to get light onto the lower leaves being sank so low into the pot. You should carefully remove the plant and root ball, then fill the pots all the way and then put it back in.

Thanks alot, got them transfered.

I'm going to go out here on a limb and say they look ok...
I mean a first grow.. figuring out shit as they go wrong, fixing things.. they look.. ok. The ph is inconsistant, likely so has the nute schedual too..the guy who looked after them tried.. by the looks of it.. just maybe not enough consistancy. Properly cared for, most of the time.. that's a good way to put it.

the little ones are a little young yet for nutes.. wait for a few weeks to avoid burning them.. seedlings are very delicate, and you can fry them if you are over-zealous in a nute regiment.

the top of your plant yellowing looks like n dif. (it's hungry). I'm just guessing, I could be totally wrong.. but, i think your caretaker made the same mistake we all make and got aggressive with the nutes. Apparently he didn't give consistant care.. may have burnt some leaves.. then caught the mistake.. and fixed it... ph COULD cause lock-out.. but it looks like it's time to nute the bigger ones.. hope I helped some.