I'll be interested to see what Teetee says about this. I'm no expert, but I've been feeding once or twice daily in coco until I see runoff at least every other watering. They say "you can't over-water in coco," but for my outdoor run in coco this season in 7-gallon pots, in mid flower I had to cut down from twice a day in veg to once a day for the last month to halt bud-rot (it worked, harvesting now). Water usage depends on temperature even more in coco since it doesn't retain much water. In Summer when my indoor grow got near 30°C I had to increase watering amount, and frequency to twice daily. Last year I was in hospital for 6 days and the indoor girls survived somehow with no watering, but the coco was bone dry, so I guess the plants can retain water too if they have to. For auto-watering I'm using an electronic interval timer to adjust watering amount and frequency. For seedlings in Solo cups I can set it to water for 20 seconds every 24 hours, or for big thirsty girls vegging in 2 or 3 gallons of coco I might set it to irrigate for 2 to 4 minutes every 12 hours. If 2 minutes doesn't produce runoff I try setting it for 3 or 4 minutes until I do get runoff to prevent salts buildup (I'm feeding 2.5 grams/gallon of MegaCrop 1-part for most of the life cycle). My runoff drains into a bucket so I can keep track of the amount, or into a condensate pump.
