Plants dying? Bugs? Lack of something?

[jdawg21]

Plants were clones that I got from a friend, started yellowing when I got them into my tent and have progressively gotten worse. Idk if its a lack of something or maybe bugs? I know there are bugs flying around inside the tent and around the plants and soil maybe gnats? Plants are under a 250W HPS bulb for 24 hours straight with an umbrella type hood. Temperature is between 75-80F. Humidity is around 30 which I was thinking was two low.

Any help or any other information that is needed or given will be very much appreciated.

Thanks