Hi,
Take a deep breath! your going blue LOL.
Ok the very first thing is get rid of that carbon JMO. after 5 - 7 days carbon throws back all the bad it took out of the tank with intrest, so in my oppinion that is a no no.
now with the GH and \KHgiven ph crash shouldn't be a problem and i think your ph is low for the GH/ Kh given so i would try not running your tap water over peat just to see what happens, also you said peat granules in the filter? what is the ph of the aged water b4 adding in the tank?
try mixin ro with tap 50/50 and see what the perams are.
As to your question what to do now Raising perams is not a shocking to discus as lowering them so don't worry do it over a couple of water changes.
my approach would be..... get your water correct for the changes trying what i suggested if you like and then just keep changing water as per normal after a couple of quick changes.
Sorry if i didn't type this out methodicaly ask questions if you like.
HTH
Good luck and welcome.
Larry