Anode ideas for spa copper heater
 

I have a spa that is heated by hot water passing through copper pipe
under the seats. I have had problems with corrosion due to the
chlorine and other water issues. I have coated the heater tubing with
epoxy, but it still gets nicks, and corrodes. I think it would help to
add an anode with some kind of clamp around one of the fittings. Does
anyone have any ideas about the best material to use for the anode,
and the best way to "make it happen"? There is a fair amount of room
under the seats.

Bob