My first Mars 1200 i ran very hard 24/7 veg and humidity was up to 80 plus humidity and 90 plus Fahrenheit during the low weather fronts. Light had about 6 months on it ( two grow cycles)when I noticed one square section of diodes had gone out in the corner. I was sent a new DRIVER (black box with circuit board semi sealed inside) and I was able to replace the driver fairly easily and fix prob. I took apart the driver and noticed some blown out chips( photo back somewhere prior to page 1000 of this thread). Looked like condensation had caused a short . Something had caused a short , possible when I switched to on off cycle 18/6 and the temps fluctuated too much ( 90-65) Humidity 80+ , causing water droplets inside driver. I lowered heat in grow room to mid 80ies( more fan cycles) with aux heater keeping temps in mid 70 range at night and thus lowered condensation problems. Only 10 degree fluctuation in temp is best per this thread.
On the other hand,I recently discovered( 10$ temp humidity unit from A-zon) when the weather is in high pressure mode, in my neck of the wood, the humidity drops to 16 ( not so good , possible causing crunchy fan leaves or so I thought. The crunchy leaves could have been a lack of oxygen due to algae and bad air pump diaphragm heating up res. All happening at same time so go figure) and I have to add moisture to the air and try and maintain that 50-60% for veg( wet towels or humidifier). I also reduced light cycle to 18/6 for veg as recommended by MH for the 1200.
My experience is for mediumless RDWC. I see you are using coco so you may have slightly different factors.
Basically 50-60% humidity (at plant level) for veg n 40 for bud. Temps of plant leaves 84 F day/74 F night. Root balls in hydro res 65-70F ( not sure about coco roots temp), higher for seedlings 84F. Bush trim once a month .