Indoor Multi-strain Madness!

I'm having trouble diagnosing the light brown almost beige spots showing up on the plants. I gave my friend the hash plant head of lettuce looking plant this week so I could focus more on the 3 plants. I am down to 2x Toronto Cookie plants which are growing the best and one Sativa Blue Dream which I've struggled with from the start. She grows thin wispier leaves and seems to be a lot more sensitive. She is showing classic calcium deficiency right now even though I've added the Cali Magic. I started adjusting my PH down to 5.8 in hopes to correct it. Blue Dream and TO # 1 have been trained with a sort of quadline method even though I kept the 2nd node along with the 3rd and 4th. So they essentially both have 6 shoots growing their own offshoots which I've trained to be equally spaced around the plants. On the TO # 2 plant I topped it later so it has more nodes. I bent the main stem right over to spread the auxin on her and she is doing well. Kind of just shooting by the hip with her training and learning as I go but it seems to be going very well. Both TO Cookie plants were trained extensively at the end of this week and likely for the last time as all their shoots are out past the edges of the pots now and canopy is looking fairly level. I will let them go vertical now for a week or two and then flip to flower. Blue Dream as usual is giving me a run for my money but really started to pick up last week. Her nodes are intensley tight and bushy. I measured 3 nodes in 3.5" on most shoots making it very hard to train. I think I will defoliate a bit to open them all up next week. Here are some changes made that seemed to have helped the slower growth and issues I;ve been facing, I've certainly learned a lot on this first indoor grow! Low night temps dropping to 16 celsius when lights went out (canadian basement) - switched lights to 24/0 schedule to maintain 24-26degrees Insufficient lighting - upgraded to a MARS Hydro TSW 1000 quantum board Poor watering techniques - watered no more than every 4 days. Lightly top watered if bottoms of pot werent dry. Overaggressive training too close to the main stem knuckle causing stem breakages - Learned to start bending further down at newer bendier growth No added CalMag supplement in soil less medium - Added Cali Magic, lowered PH to 5.8 to correct lockout if it was present Light too close to plants - Raised light to 28" Insufficient fresh air movement - Added 2 interior circ fans, 1 4", 1 6" and turned on 4" inline exhaust fan. Added a 12" fan outside the tent on low pushing air into the intake. Nutrient Burn - I started noticing the tops turning yellow and clawing downwards - next week I will reduce to 1/2 strength nutrients.