I have no Idea

I am new to the growing side of the house and have been having a few issues lately. I have read a few things that suggest one problem, but the again others that suggest another. I will just put what I can down and see what you all have to say.

I have a dozen plants all about 2 months old in a closet grow room. I have a 500w HPS light and a 15w grow light on the plants. I keep the temp at a constant 78 and humidity relatively high. The plants are in smaller pots still because they haven't looked healthy enough to move....

Most of the plants are 24" tall and growing slowly and I have noticed the tips of the blades (teeth on side of leaves) turning yellow green. I figured this was due to over nutes and have just been watering, with no improvemnt. I cut back on watering until the plants were getting saggy (twice) and still have yellow blades. The temp at bottom of plants is 78 and tips is 78 so they aren't getting burned... what could be the deal. I must add, that air curculation isn't constant I open it up and hit them with a fan about every 4-8 hours...

Marijuana wants a lot of root room!

Small growing conatainers will cause A LOT of problems.

Transplant them to something larger.

thats funny never heard of 500wHPS before????? and with a lets say 400w hps the 15w is a waste!! all plants dont matter what your growing should have fans on them at all times.sounds like low N AND needing CO2 and fans,air,something so thy can breath!!

how many times should you water a day during vegg?

do the finger test to tell you when to water.. put your finger in the pot, and if it feels dry down to around two inches or so, they need watering.. this is another benefit of being in a bigger pot. a bigger pot will allow you to water them less frequently as there would be more soil to hold the moisture in..
you can also go by the weight of the pots, but this takes a lil experience to learn when they feel light.. just get a feel for how heavy they are after you water them, and check on them, and when they feel light, water them.. i like the finger method myself, but to each their own really.. whatever works for you..
i will say this.. i have mine in a lil under a three gallon pot, and they only need watering around every third day or so..

Haha, yeah thanks GreenPeace, I fat fingered the 5... I will make sure to get them into bigger pots and make sure there is a constant flow of air from here on out. I was hoping to keep the smell down by only airing them out a few times per day but it's time to spend the needed money and get a filter and blower. I have 2 1000W lights but was told they would be too hot for a closet grow. I will have to find space to build a grow room and stop half assing it.

more light equals bigger yields. dont expect the leaves that were damaged to get better. are newer leaves getting the edges? check for that, dont look at old growth as much harder to read that.