Pool Salt Information

Salt water chlorine generators (a.k.a. SWG) requires the addition of salt to the swimming pool water to facilitate the generation of chlorine gas which is instantly dissolves back into the water (how it works is for another time or link). By now hopefully most people have learned that not all salt products are appropriate for swimming pool use. Contaminants in salt can create other problems for the pool owner, so it is best to use one of the products that are intended (or acceptable) for use in swimming pools.

While I am sure there other products acceptable for use in swimming pools, I have always had very good luck when using Morton salt products. I used Morton Pool Salt to get my original salt level up (about $10 for 40# in my area), to maintain my pool salt level I have switched to the same Morton System Saver II Pellets (less than $4 for 40#) that I have been using in my water softener for about two years. At first I was using a “chlorine floater” which worked fine but took forever to get 40# into the pool. Now I have a 5-gallon bucket that I drilled a bunch of holes in, which I can put in the whole 40# of salt (with a concrete block over the top to keep it from floating). All the salt is dissolved in less than an hour and the bucket keeps it from staining my plaster.

I heard back from Morton today when I questioned them about the difference between the two products and/or their safe use in swimming pools. Here is their answer:

“Morton Pool Salt is a plain salt product. Morton System Saver II pellets contain resin cleansing additives. Water softened by pellets is drinkable; however, if you have any type of specific health concerns, please see your doctor. Either product can be used in your pool.”

Horsepower Rating

If you have wondered “what is the difference between Full-Rated and Up-Rated horsepower for pump motors,” you are not alone. While I figured out it seemed to be a marketing distinction (a.k.a. ploy) by looking at the flow curves for my Pentair WhisperFlo pumps, the on-line retailer POOLplaza has a short article explaining how this slight of hand is executed. The bottom line is “use the pump/motor curves” for making your choices.

My earlier post “Pump and Motor Efficient Sizing” is related, and may be of interest at this time.

Pool Electrical Hazards

While electrocution in swimming pools and spas are relatively rare, last October Pool & Spa News had a good article “Shock Waves” about the hazards associated with electricity and water, especially in older construction. Also, they provided a link to a Consumer Product Safety Commission safety alert about providing ground-fault protection for pools and spas.

The Pool Biz

The Pool Guy's The Pool Biz blog which primarily addresses his concerns and problems with salt water chlorine generators (a.k.a. SWG). This site is very opinionated but definitely worth a check if you are planning on adding a SWG to your existing or new pool. He appears to be a pool builder and/or service provider in Texas. It is quite obvious that he has a chip on his shoulder but it appears that his intentions are to honestly inform the pool owning public about his concerns with salt added to pool water.

I have a SWG, which in my opinion has only worked marginally since it was installed during 2006 summer. I have not had any of the problems he has noted on his website, but I think one method for minimizing some of the potential damage is to quickly wash off the pool deck to minimize the potential problems associated with higher concentrations of salt on the deck from evaporation.

Heat Pump Applications

Swimming Pool & Spa Heat Pump Application (ISBN 0912524529) is as the name implies, is a book about the details of marketing, designing and installing heat pumps for swimming pools. In this 1989 book Mr. King does a good job of presenting the benefits of the electric swimming pool heat pump when compared to other types of pool heaters.

Heating System Sizing (Chapter 7) information is applicable to any pool/spa heating system. The conclusion that electric heat pumps are very cost effective is not surprising; however, I believe solar heating is equally or more cost effective in the Sunbelt when using the same criteria. Fuel (primarily natural gas) provide the quickest heat gain and can be more efficient when heating is provided only a few days a week or month. Heat pumps shine the most in areas where the pool is to be heated for an extended period of time during moderate temperatures without ample solar heat potential (e.g., out of the Sunbelt).

While I do not have a heat pump, there seems to be significant gains in both efficiency and popularity over the last decade. Here is a link to Pool Heat Pumps, which appears to be an informative and helpful on-line retailer.

Pump and Motor Efficient Sizing

This seems to be one of those topics that have a many different opinions. Before starting construction on my pool I spent time researching information on websites and still did not come up with any specific conclusions. One thing that most pool owners agree about is that pool circulation pumps use a lot of electricity (this seems to be one of the biggest complaints among new pool owners – I’ve lost the link to this forum topic).

I have to admit that I did not fully believe the information available, so I ended up with a 1.5 horsepower (HP) pump/motor for my primary circulation system (down from 2 HP that the contractor originally recommended). One of my reasons for keeping with a larger pump motor is that my solar heating system returns directly to the spa (allowing the spa bypass to be closed), which is separate from the pool return line where salt water chlorine generator is located (needing its own flow to operate properly). This feature keeps my spa warmer (5 to 15 degrees F) than the pool water that is pumped into the solar panels (more later).

This University of Florida, Pinellas County Extension, “Timely Topics” article titled “Energy Savings For Your Pool” does a good job of explaining the basics of hydraulics associated with the swimming pool circulation system. While the comparison table for pipe size and pump motor HP makes sense for single line systems, many newer pool circulation systems have multiple suction and return pipes, which increases the actual flow [e.g., my 1.5 HP system frequently pumps about 110 gallons per minute (gpm) because it draws from two or three 2-inch skimmer/vacuum lines and after the filter returns through 2.5-inch solar heating and 2-inch circulating lines].

Here is the first place I saw information about reducing the size of swimming pool pump motors. This guy is very rough around the edges but knows what he is talking about. “Sizing The Pool Pump” covers many of the basics particularly when looking at existing systems.

The chart in the “Swimming Pool Pump Energy Savings” article shows the approximate monthly electrical usage in kilowatt-hours (kWh) for various pump motor sizes and daily run times. Utilizing this information along with the other sites discussing circulation flow, it is possible to achieve an energy efficient circulating system. While this article touts the advantages of a two speed pump, I was not convinced about its benefit in my case because the low speeds are not capable of generating the pressure (water head) necessary for providing adequate water flow to the top of my solar panels.