Blue Diesel & Glue Auto

Well I've definitely been stressing this week. Two Of the Blue Diesels are growing Strong one is lagging behind a bit but BOTH Gorilla Glues look a bit Sick. Although everything is exactly the same for them they are NOT happy at all. Brown Spots on the leaves and the lower ones are being eaten away!! It really does seem to be JUST the Gorilla Glues that are not going well - My Guess is Calcium Deficiency but out water is VERY limescale / calcium heavy. WATERING - Im also unsure about watering and I'm sure I have over watered a bit, in these pots and with this Canna Coco professional and pearlite its supposed to be almost impossible to over water?? Should I be adding water until some comes out of the bottom or is that not done until the plants are bigger?? The two little runts I put together in the last pot re just NOT growing at all - I may just pull em up and let the three strong ones have the space. Now thinking about starting LST in a couple of days time.