oh and I dont change my rez
I refill once a week or so depending on how many plants I am running
here are the drip stakes I use now
http://growershouse.com/hydro-flow-...ack?keyword=&gclid=CICKxNyjydQCFY6Kfgodi8UEKA
I water 3x a day for 1 minute each
oh and by the way
make sure to get a small 250gph pump to circulate your res
do not bubble your res
CIRCULATE!!!!!!
cant stress that enough
set it on a timer to run for 15min every 3 hours
the way I circulate mine is I ran some 1/4" pvc up to the top of the res and put a 90 elbow on the top
so the circulation pump sucks from the bottom and spills on the top
as the res starts to drain the pump both oxygenates the res as well as circulates the nutrients