i am in the process of building a dual purpose refugium/surge tank out of a 20gallon tank. before i start gluing in the assorted bits and pieces i want to know what is safe and what is not cement wise to use. part of my surge design incorperates some stuff i had cobbled together a while ago using regular pvc cement(clear not purple). will this stuff poison my water? please help if you know, i would hate to blow this one and kill something or everything.