On average the 2 gals would last say maybe 1 to 2 weeks, not really sure, bare in mind I don't use pumps to feed, I feed as if they were regular house plants by hand, I pour in the nutes 'till pot is full and let drain out to the bucket, The grow cubes soak up some and the plant drinks some, after each 2 feedings per day ( 2 days ) that is to say 4 full feedings, an average of close to 1 gal is used up, not sure I could leave it for 1 week without plant drying out, if you were to use a pump I would have a resevoir of at least 4 gals and you should be ok for 1 week but not more, than 10 days, that's just a guess, best to try it out before you go ahead and trust it.
Here is my mix I use, this is per 4 gals, I use GH flora series, grow, micro, bloom.
for grow: 40ml micro, 60ml grow, 20ml bloom
for flower: 40ml micro, 20ml grow, 60ml bloom
Been using this mix fo some time now and have good success, 'course I adjust my ppm's after mixing, depending on plant age.
