white frost i did the same thing 5 days ago exept my water was 40 degree for some strange reason i thought i had warmed it up well any way cut long story short i mixed nuute soup up ph'd it to 5.4 an then put in my system, the next day i chek the ladies there exactly the same no growth so i checked all my meters ph perfect ppm perfect water temp 43 degrees this is when i realised what a stoner i was 3 days later an hooray new growth about an inch so i must of shocked em for 3 days i foilar fed beacause i thought they were stunted i just used ph'd water with a drop of superthrive an some root enhancer i had , they had no leaf disscolouration no deff so all in all it was a lucky escape, on a side note i would not worry too much about 60 degrees as this is the temp i keep my girls in between 60-68 degrees my tap water is 40 degrees it it reaches 70 i put 4x 2 liter frozen bottles in the rez an let the pump recirculate the water round the system an hoopla back to 62-64 degrees, it takes about a week to heat up to round the 70 degree mark as i have them wrapt in foil bubble wrap insulation jus my 2 pennies but yes i would not stress couple of day they will be right as rain