just figure 1 1/2 gallon of soil for each month of growth regardless of lightingOn a side note..how did you come up with the pot sizes? Just asking cause 3x 15 gallon pots for 400 watts worth of light seems a bit much. I do one mother plant under a 600 watt in a 15 gallon. Ample root space is definitely a good thing, but the amount of growth and transpiration of water is limited by how much light/energy the plant has access to. You dont want the grow medium to stay wet for too long in between waterings,especially in a small space, as it can lead to humidity and rot/mildew/mold issues.
Your cfls equivalent wattage is not the wattage you pay attention to.
8x23w=184w. Not 800w.
You could get by on the 250w MH over 3 mothers but it all depends on how many clones you need and how often you need them.
J
I know 15 gallon seems a bit excessive, however they are all 3 reveged from being budded out in 5 gallon pots and I read everywhere and it was my understanding that when doing a reveg you must bump up pot size, also they would get root bound fairly quick I would imagine. Once I get them going really well and am pulling off some good cuts I will grow out the cuts into moms so I don't have to keep them in such big pots......I hope this makes sense, one of those things where I was unable to take cuts prior to flower and want to keep the strain alive, it was incredible