In one sense, the REAL question is, What do YOU think about the copper system?
Systems like yours:
1. Normally cause some staining (blue / green => copper; black -> maybe, copper; gray -> silver.
2. Cause blond -- and sometimes, white -- hair to turn green
3. Kill algae, and inhibit bacteria, BUT
4. Do NOT kill bacteria quickly, or viruses, at all.
5. Can't oxidize people goo, so you have to use chlorine, peroxide, monopersulfate, or something else to do that.
On a pool like yours, with the BBB method, you should be spending lest than $250 per season and less than 1 hour per week on chemistry. If you're spending more time or money than that now, you might want to change. However, the Cu/Ag systems ARE better when you go on vacation, than chlorine. You have to have help, or a careful plan, to avoid a green pool on return with chlorine alone.
Also, because Cu/Ag pools are not sanitized -- they have no virus killing residual, and only a very S-L--O--W bacterial kill rate -- they are not safe for swimming with non-family members . . . or even with some family members!
But, if you've already used it for 4 years, I'm guessing the problems don't bother you? If you just want to get a better handle on your pool, the first place to start with is with correct test kits -- see the test kit info page. Even if you don't switch, you can use the info here to improve your operations.
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