the slower the better,I broke her total amount to three equal parts being added every two weeks.If you have sps and go to fast it will shock them very hard.This is one of those things that patience pay's off.If you see a drop in Ph as slapshot suggested in a another thread don't get to worried it comes back up fairly quick.I noticed a 0.1 drop for two day's then it returned to it's normal level of 8.3.Hope this helps