Im still having troubles figuring out how much water to be giving them

Their both showing pistils now one is 10 inches the other is only 6 both in 3 gallon pots..
Ive only been giving them 500ml of water each every 2-3 days 1 water the next grow or boost nutes..
I'd prolly need at least 4 times that much to get runoff..?



Peace