So I've never really had a science when it comes to watering, i use a combinating of the "2nd Knuckle" test and a cheap moisture meter to see when the plants need a drink. Now I usually just pour some water in the soil until i feel its enough, but exactly how much (ounces, liters etc...) liquid should they be getting each time in the 3 gallon pots? Just an FYI...I have gallons mixed nutes and gallons mixed with molasses and cal/mag sup, I alternate between the 2 for waterings. So water with nutes then next time water with molasses and cal/mag..and continue back and fourth.