You don't need to boil your water, it won't affect metals anyway. All that will do is kill bacteria and dissapate chlorine.
If you cannot afford and RO
as yet, use an additive that binds these elements. Seachems Prime is an excellent additive that will render most metals harmless, removes chlorine and breaks the bonds of chloramines. It does not contain aloe so it will not cause the skimmer problems. Add some carbon to your system and it will remove the bound elements completely. Alternately, you could buy you water from the local grocers. Typically it's not that exspensive.