HELP! yellow tips and lower leaves.

im using potting soil from walmart, other than that i have the fox farm trio, and i use distilled water, i do not have a ph kit atm, i know this isent good but i dont have much to work with temps are 75-80 day and 70-75 at night im using two 175 watt cfls, the plants are both a month old from seed but im gettting some yellowing on the lower leaves of one and tops of the other any advice?

Looks like it needs some nitrogen. Give a little of your grow formula and wait about a week to see if it helps.

would it be okay to pull the yellow leaves?

I usually just leave them. Some of them will turn back to green if it is from low nitrogen. The real yellow ones will just drop off though.

PH meter is probably the most important tool you can get though... imo.