Do low calcium levels needed for Cleanwater Blue increase the risk of corrosion?

[bowdrie750]

I am considering switching to cleanwater blue but I am concerned since it only works with a very low calcium levels.  My last hot tub did not last very long because I did not routinely add calcium to my soft water at startup and my hot tub suffered from severe corrosion due to low calcium levels (had to replace tub after 3 years).  My understanding is calcium must be between 150 to 400 ppm to prevent plumbing corrosion issues.  Cleanwater blue does not give any information about preventing pipe corrosion due to the low calcium levels needed for their system and I am hesitant to use it if it is going to shorten the life of my new hot tub.  Does anyone know if the copper ions will minimize corrosion due to low calcium levels or will hot tubs using cleanwater blue simply need to be replaced more often?

[TwinCitiesHotSpring]

sorry but your information is incorrect...Calcium kept around 150ppm is ideal in my opinion, and some systems such as Saltwater chlorine generators like it around 50-100ppm.  If you run your spa at 400ppm calcium your are going to run into some issues: calcium flaking in the water, buildup in your pumps, ozone injectors, check valves, etc. and it can even begin to attach to the shell (I've seen it so bad where an acid wash was necessary to remove it)

I'm not familiar with copper systems, but keep in mind there is only a few sanitation methods that are EPA approved: Chlorine, Bromine, Biguanide, and silver ion/mps....A copper based system is NOT epa approved to use in a hottub as a standalone product just so you know

[chem geek]

Metal corrosion comes mostly from low pH and other factors such as dissolved oxygen.  It can also come from dissimilar metals via galvanic corrosion or from stray currents via electrolytic corrosion.  It can also come from physical effects such as too high a water flow for the plumbing or with plumbing that has bends that are too tight via impingement corrosion.  Calcium carbonate saturation is not a reliable way to prevent metal corrosion (a technical discussion of these among corrosion experts is in this link).  As was noted above, you usually don't want the CH to be above 150 ppm in a hot spa (at usual TA and pH levels) or you risk getting scaling which can burn-out a gas heater (scale builds up in the heat exchanger because it is hotter and the scale prevents the transfer of heat so the gas heating builds up temperature of the metal to the point that it can weaken and leak or where other components in the heater get damaged from the heat.

Copper ions alone do not even kill fecal bacteria.  See this post for more info comparing chlorine, copper ions and silver ions.