It was my understanding that E-Z Pool/Chlor-Free is not biguinide but some sort of propiretary mixture (I would guess sodium percarbonate as the main ingredient since it's level can be tested with DPD) that is supposed to eliminate the need for chorine. I don;'t believe it is EPA approved.
http://www.americasbestpoolsupply.co...1/PageNumber/1
http://www.ordinis.com/chemistry/e-z_pool.htm
http://www.rogerspools.com/chemical.htm
There is also an ionizer called Chlor-free.
http://www.chlorfreeglobal.com/how_works.php
http://www.chlorfreeglobal.com/product.php
In either case I would have the water tested for metals. I would also recommend switching to chlorine.