check your nuets. it sounds like that one other thing that all your grows have in common is yor nutes. check that you arent mixing them in the wrong order if they are three part nuets i beleive that there is a specific order that you need to follow or maybe they are contaminated. i use a 7 9 5 1/2 tsp. per gallon of distilled water @5.7-6.0 ph. for the first seedlings after that use i 1tsp. of 10 5 5 per: gallon 1tsp 7 9 5 per: gallon and 1 tsp 3 12 6 per: gallon i use a three gallon resv. change out every week i use nutes to adj. my PH every other day and distilled vinegar to lower it (both of these lower PH. the reason i use nutes to lower my PH is because i only use 1 tsp. of nutes per: gallon to start off with so when i use nutes to lower my PH i wont over fert them i dont know man works for me and my plants very well!!!!! no one told me what to do i kinda of just did some research and came up with those mixtures o yeah my nutes of choice are dyna-grow and superthrive and some co2