I am the manager of warranty service for a major manufacturer.  One of my customers has provided these pictures, and asked for our opinion of the cause of the white deposits around the surface.  Can you help?



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To: John

The pictures indicate a common problem associated with hard water that is prevalent in many areas of the country.  You probably have experienced the same hard water problems in coffee makers, bathtubs and shower devices.  They are found frequently on household faucets, drains and bathroom grout.  When appliances are not regularly cleaned with products formulated to remove calcium (e.g. Lime Away®), they develop deposits of the chemical salts present in hard water.  These deposits are basic, and need a weak acid to dissolve them.   When commercial products do not do a complete removal, a stronger acid solution is required.  An economical and readily available product, muriatic acid,  can be used.  Muriatic acid is actually hydrochloric acid, and is commonly used for swimming pool water chlorine maintenance.  However, it must be diluted with water before use in removing hard deposits.  Muriatic acid is a strong oxidizer, and should be used very cautiously.  It is also recommended to use heavy kitchen-type latex gloves, goggles, and a chemical cartridge respirator with cartridge(s) when using strong acid solutions.  You can also refer to the safe handling recommendations of the manufacturer of the chemicals.  A fan can be used to blow harmful vapors away from the work location.  Pure acid is likely to do damage to some surfaces, so it should be diluted using equal amounts of acid and  distilled water.  You may even want to test a small area to confirm that it does not attack the surface.  Be especially careful using it on vinyl covers, electronic devices and other plastic components within the spa.   Apply the solution with a clean towel, scrub with a nylon bristle brush, and rinse with clean water.  You may need to repeat the process to remove 100% of the deposit.  A wet/dry vacuum can be used to remove the acid solution and rinse water.

In order to prevent a new build-up of calcium, the owner should use calcium deposit removal products in a regular maintenance program.  The frequency will depend on the hardness level of the water, and the frequency of total water replacement in the spa.  It is also imperative to maintain overall water chemistry.  Improper use of water chemicals can also lead to deposits.

Total hardness is one measure that is used to maintain water chemistry.  It is a measure of all the dissolved minerals such as calcium, magnesium and sodium. For practical purposes, calcium hardness is the common reference used in pool and spa water chemistry.  The recommended level for calcium hardness is 200 – 400 parts per million, and both high and low levels can result in problems.  It should be closely monitored.

High calcium hardness results in scale formation on surfaces as well as scaling in the pipes, plumbing and filter. In extreme cases the water becomes dull and cloudy with the calcium precipitating out into the water rather than onto a surface.  High calcium levels will also irritate users, causing sore eyes as an example.

If high calcium level is a result of spa chemicals, draining some or all of the water and replacing it with fresh water will lower calcium hardness.  If the cause is the fill water, commercial hardness reducers or chelating agents will bond with the calcium to keep it trapped in solution.  If the user is uncomfortable using the home kits for water maintenance, a professional can provide the service at most spa/pool dealerships.

I hope this helps.

Ken Wolfe

Consulting Chemical Engineer