If you switch to 1gal fabric pots and put them on a flood table you can just flood the table once or twice a day. Coco soaks water up through the fabric like a sponge. Hand water once every week or two from the top to rinse excess salts and you can grow monsters in those little pots. I've gotten...
Absolutely gorgeous plants. I bet they smell amazing. I wish I could grow a few outside without giving up my freedom. I'm stuck in a weed Nazi state between fl and ms. One day though.
Once a week or once every few days should be fine. Looks like low N to me. Sometimes the leaves on the inside bottom of the plant that don't get enough light will yellow and fall even if you're doing everything right. If the ebsome salt doesn't work try folier feeding with 1/4 strength veg...
Mars hydro 300 calls for no longer than 18 hours before giving it a rest. Anything over that is asking for heat failure on a driver. That's why you hear about people with half their light out. They most likely ran it for longer than recommended without a break for cool down
Bury 6" or 4" pvc. Run at least 100' about 24" underground. Stub one end up with 2 90° elbows at the end to keep rain water out and stub the other end into your shed. Then you can get a cheap 4 or 6 inch fan to suck cool air from the pipe into the shed.