Variable Speed Pump With A Salt System
Like it or not it will soon be law that all swimming pool filtration systems use a pump that meets a minimum efficiency requirement that only variable speed pumps will be able to meet. This is a move to reduce wasted energy utilizing new pump technology since the traditional method of filtering swimming pool water is actually, by and large, a very wasteful process. Despite the frustrations from pool owners who are forced to invest in these more expensive variable speed pumps this is a move to improve the industry as a whole. Variable speed pumps do in fact use far less electricity to move a similar amount of water as a single speed pump, however to get the maximum benefits from this new pump technology you will need to learn more about how to program a variable speed pump for maximum electrical savings.
If you have a swimming pool with a salt water chlorinator system and you are shopping for a new variable speed pump you might be concerned about which pumps are compatible with salt water. It can be a little confusing to swimming pool owners with salt systems since most pool pumps, when you read the complete care and warranty information, state that they are not for use with saltwater. This confusion comes from pool owners with salt water chlorinators misinterpreting this a problem, which it is actually not. When a pool pump talks about not being compatible with saltwater, or most pool equipment for that matter, this is actually referring to sea water systems and not salt water chlorine generators. A pool with a salt system will have a salt level somewhere around the 3000 parts per million range, where ocean water or sea water will be closer to 25,000 parts per million or more. Consumer grade pool equipment, like pumps and filters, are not suitable for ocean water systems as the level of salt is too great and will likely damage the equipment. This is why the manufacturers put this warning in the literature for their equipment.
Variable speed pumps compatible with pool salt systems - Other than the most entry level above ground pool pumps made for temporary pools, pretty much every brand, make and model of pool pump is compatible with salt chlorinator systems. This, of course, assumes that the pump is installed (and operated) correctly and that you include the pump with the bonding grid that protects your pool and your pool equipment. If your pump is installed correctly, and electrically bonded as all pool pumps should be, then you should have no problems with your pump as a result of having a salt system installed on the pool. For more information about bonding systems and how to connect your pump you can read this article about why pool pumps fail.
Pool Pumps Compatible With Salt Water
While almost all variable speed pool pumps are made to be compatible with salt water chlorinators, usually up to and including 5000 parts per million of salt, this is not to say that damage will never happen as a result of the salt. Having elevated levels of salt in your pool water can have a number of adverse reactions that could potentially damage your pool or your pool equipment, but probably not in the way that you are initially imagining. Most pool pumps do not have exposed metal components, like a pool heater for example, so there is not an immediate concern for corrosion damage. What is very significant however is the fact that having a salt system on your pool can and will change the way that you need to manage your water chemistry...and not all pool owners appreciate this enough until they are facing expensive (and early) repair bills.
Of greatest concern with a salt system is that the water chemistry in your pool will require a different maintenance schedule than normal. Specifically the pH on salt water pools is almost always high and will require constant corrections to maintain within the correct range. This is an example where a variable speed pump could be damaged by a salt system, but not as a direct result of the salt itself, but as a result of chronically poor water chemistry. Having your pH above 8.0 as most salt pools typically are means that your water is ten times more basic (alkaline) than it should be if you maintained a pH of 7.0 or just a little above. Additionally a salt chlorinator system does not know that the chlorine levels in your pool are getting too high. If you set your salt system to too high of an output, or otherwise forget to monitor your chlorine levels, you could end up with chlorine levels far above what your pool system should be at.
Failure to maintain the pH level as well as the sanitizer levels in the right range could potentially damage your variable speed pump over time, but this is not a function of having a salt system, but instead a failure to understand and properly manage water chemistry levels. This could happen with any pool, but salt pools do have a reputation of being chronically mismanaged. The potential for damage from poor chemistry goes even further than this since having high salt levels combined with high pH creates a potential for scale to develop in your water. Just as with high pH (or low), as well as high sanitizer levels, development of scale can cause poor operation and eventual damage for the moving internal components of your pump. In total it will be critical for the long term operation of your variable speed pump to learn how to maintain the water chemistry specific to salt water pools. For more information you can read this article that talks specifically about how to maintain a salt water pool.
Motor RPM for salt systems - Something that pool owners with single speed pumps did not need to consider is the flow switch for your salt water chlorinator. All salt water systems have a flow switch for safety which detects adequate flow which then allows the cell to start generating chlorine. When you add a variable speed pump to your pool system you now need to consider at which speed the pump needs to run in order to have enough flow for the flow switch to close. Further to this even if you determine the RPM your pump needs to run at to close the flow switch, you need to appreciate that the flow rate in your pool system will change with changing filter conditions. If you set your variable speed pump at a certain speed in order for your salt system to turn on and run, you may need to change this value as the filter becomes more dirty. For a given motor RPM you will move less water through a system with a dirty filter than one with a clean filter. For this reason you typically want to overshoot the minimum RPM value needed to close the flow switch on your salt system by at least a few hundred RPM to help avoid this problem.
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