Suggestions for sacrificial anode to protect copper?

I have a hot tub that is heated with a copper pipe unter the seat carrying hot water. I just replaced it after 10 years due to leaks
caused by corrosion. I'd like to use an anode to prevent re-occurance.
Is this a good solution for a chlorine water environment?
Does anyone have any recommendation for the best metal to use for the anode? Goals -protection, life, cost.
Also, for Seattle locals - A good marine supply place to buy it, if that's the best place to get it? (NW Seattle)
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