hi i have just changed my membranes and prefilter on my merlin RO ,but the tds is running at about 135 and has been for last half hour ,it does say rinse for 2 hours if using for drinking water ..does anyone know how long it should take to get it to run properly ,it used to give me a tds of 7 or 8 but lately it has been running at 10,11,12 13 thats why i changed them..Help Please