LSD White Auto Feminised NOOB

I ended up changing the fairly minimally sized reservoir at day 49(technically week 7). Added the usual 2ml per litre of Micro, Grow & Bloom(PH Perfect) with addition of 2ml per litre of Big Butt. Also about 1.5ml per litre CalMag,. I have left the halo sprinkler on a timer & it gos for about 15 mins every hour though I assume this is not necessary as I have an air stone & bubbler going 24/7. Lots of white pistils now & pretty flowers all over. Under a microscope there are lots of clear trichomes on the leaves, Nearly a disaster as my leaves seemed to be getting 'rust spots' everywhere & it seemed to be spreading quickly. Research led me to the conclusion that I had two problems - Calcium deficiency & Nutrient Burn as the tips of my leaves were browning & curling upwards. I halved all Nutrients to 1 ml per litre but doubled the CalMag to 2ml per litre(was only using 1.5ml per litre before). My PPM was 1500 so I tried topping up with plain water at first but I think I had what they call nutrient lock out & this didn't seem to be slowing the spread of babyshit brown. I then flushed my reservoir with tap water & refilled it with half of the Nutrient strength. Fingers crossed as it looks better now & the PPM has been steady over 12 hours or so at 800. See pic of sick leaves above. Also I would not recommend Hanna PH meters - I have had two, one of them was new & they are shit considering their price. I have ordered a different 'cheapy' & will keep u posted. Strips till then