i too think its a shame you chopped so early......but not everyone knows when its time. next time you should post pictures before you chop and get some pointers....... you can say you did that on purpose and chopped it according to your liking.....but that makes you look silly, just ask next...
8/16 is ok if in flood and drain- or soil......but dwc the roots are in constants nutes..... 1300 is way to hot. id try 2/4 with some grow get ppm around 500 and see how they respond... if you use cal/mag id us no more than 50ppm in dwc...
keep your ph at 5.8 let it drift to 6.2 but nomore than that....you need to get your ppm down to 300 and let them recover....water temp shoul be 70 at al times......freeze 2litler bottels if you dont have a chiller
sounds like nutes are way to hot....stop the cal mag asap! whats your water temp? do you have an air stone in your rez? get a picture of your roots if possible too..they tell a lot of whats going on....