you keep adding salt until your reading is right.. they is no set amount of "cups" to use.. and u should have waited til the salt was right to put the sand in cuz the sand will hold the salt for ages, and u run the risk of putting way too much in as its not dissolving fast enough so u think its wrong and add more salt thus making it too high.. as for the filter.. turn it on....... it shouldnt break, its a filter, there to get rid of crap and stuff from the tank water.....