Pool Water Chemiclas

[gregs]

I am looking to get some idea of how corrosive "normal" pool water is. That is normally maintained and chlorinated pool water. What I am considering doing is to connect my geothermal heat pump into a swimming pools filtering loop as it is currently set up as an open loop style using well water. What I am considering doing is to add connections into the filter/pump loop of the pool and to add a fountain head to help displace the heat when the a/c is running in the summer and switch back to the well in the winter. My main concern is how corrosive the water is and will it attack the copper piping.

[chem geek]

I am looking to get some idea of how corrosive "normal" pool water is. That is normally maintained and chlorinated pool water. What I am considering doing is to connect my geothermal heat pump into a swimming pools filtering loop as it is currently set up as an open loop style using well water. What I am considering doing is to add connections into the filter/pump loop of the pool and to add a fountain head to help displace the heat when the a/c is running in the summer and switch back to the well in the winter. My main concern is how corrosive the water is and will it attack the copper piping.

If your pool is manually chlorinated with chlorine (i.e. not a saltwater pool with a chlorine generator - SWG) and uses Cyanuric Acid (CYA) to protect the chlorine from sunlight, then the pool water is quite a bit less corrosive (by over a factor of 10) than chlorinated tapwater that typically has around 1 ppm FC or so with no CYA. Some municipalities have switched to using monochloramine also at around 1 ppm and would be less corrosive than chlorinated pool water.

By far the more important factor is the pH so just be sure to maintain the pH well above 7.0 (7.5 is typical). The copper piping should do fine with the pool water. Most tap water is closer to 8.0 to intentionally protect against corrosion in copper piping. If your salt level got high, then there would be more cause for concern but even then the corrosion rate is still slow, though not as slow.

If you shock your pool with chlorine, you should bypass your geothermal pump and piping just to be on the safe side though even at shock levels there is about a third of the disinfecting chlorine than in 1 ppm FC with no CYA.

Most pool heaters used to be copper. They have switched to titanium in some heaters mostly to handle the higher salt content in SWG pools. Also, the higher temperatures in the copper heat exchanger increase reaction rates including corrosion.

[gregs]

I would have thought just by the smell and the fact that you are constantly adding chlorine that the levels would be much higher. Would there be any future problems with the pool running the ph level closer to 8.0?

I havent found much info about the idea of tying a geothermal heat pump into the pool but I think it is worth a try. It would operate very similiar to a pool heater except it would be rejecting heat in the summer and cold in the winter, so I will have to watch the tempature in the pool as to not make it uncomfortable if it would get that warm? Thanks

[chem geek]

I would have thought just by the smell and the fact that you are constantly adding chlorine that the levels would be much higher. Would there be any future problems with the pool running the ph level closer to 8.0?

I havent found much info about the idea of tying a geothermal heat pump into the pool but I think it is worth a try. It would operate very similiar to a pool heater except it would be rejecting heat in the summer and cold in the winter, so I will have to watch the tempature in the pool as to not make it uncomfortable if it would get that warm? Thanks

Do you mean the smell of concentrated chlorine when you add it or the smell of the pool water itself? Pool water should NOT smell much at all. If it smells bad, then that usually means you have combined chlorine in it (monochloramine which is chlorine combined with ammonia). A properly maintained pool has virtually no chlorine smell to it at all or if it does then it's a faint "clean" chlorine smell like extremely diluted bleach.

You constantly add chlorine because it is constantly getting used up and converted to chloride (salt). It is not building up, especially if you test the levels regularly. If you run the pool pH closer to 8.0, then that is fine but it has some implications for your use of the pool. The human eye is closer to 7.5 in pH so 8.0 might start to be a little more drying or stinging to the eyes. The higher pH makes a pool more saturated in calcium carbonate so you need to lower your TA and CH levels accordingly (if a vinyl pool, then the CH is probably already low). I do not think it necessary for you to run the pool at a pH of 8.0. If you run at 7.5 or 7.7, then that should be fine. Remember that 7.0 is neutral and that the water is buffered against pH changes.

There are heat pumps for pools. Take a look at this link, for example.