After resurfacing our swimming pool there was, in a relative short time period, an undesirable increase in the level of cyanuric acid. Because of this, a refill was necessary to reduce/eliminate the current level of the acid. This problem resulted in an increase in my sensitivity to the importance of maintaining good, consistent pool chemistry over time of all their key metrics; i.e., not just chlorine and pH. Because of this, I did some investigation to determine what should be done differently to improve our pool’s maintenance process.
From Google searches, I learned how chlorine tablets can dramatically increase cyanuric acid, which is to act as a chlorine stabilizer, to an unacceptable level in a very short period of time. An optimum level of cyanuric acid is desirable, since this chemical helps increase the time for chlorine depletion. Too much cyanuric acid blocks the effectiveness of chlorine. From these searches, it was also suggested that one should purchase a Taylor K-2006 test kit, since it is difficult to get accurate pool chemistry readings from common-place chemical test strips.
After the pool’s refill, I thought that it would be good to use a Pool Service company to get going in the right direction relative to overall pool maintenance. However, I was amazed that the pool service owner used only chemical test strips for our pool’s evaluation and simply poured in the pool a couple gallons of liquid chlorine and a gallon of acid, which I had on-hand.
For this, he charged almost 4 times his regular maintenance fee? I knew from my research that probably something should also have been added to adjust the pool’s alkalinity and calcium levels. I also saw his strip test result and it sure looked like the pool’s cyanuric acid was about zero, where his interpretation was that the acid level was looking good.
I then took a pool-water sample to the pools supply company that I normally use for their free evaluation. Their test indicated that calcium and alkalinity needed to be increased in the pool; however, they said the cyanuric acid level was looking good, which was not consistent with my strip-test evaluation. I continued to use the pool-maintenance company for several weeks with e-mails to them showing the results that indicated that the pool’s calcium and alkalinity levels need to be increased. The pool-maintenance company did nothing; hence, I stopped their services.
I did purchase the recommended Taylor K-2006 test kit, which initially looks intimidating because there are so many solution bottles to use when conducting the tests; however, the instructions are clear and the results from any given test has less subjectivity than what one would get using pool chemical test strips. The Taylor test kit gave a similar answer to my conclusion relative the current pool cyanuric acid level; i.e., that the acid level was minimal and should be increased to stabilize the pool’s chlorine decay.
Because of the above finding, I started questioning the accuracy of the pool supply company’s test measurements and decided to conduct a measurement systems analysis assessment, not unlike what someone might conduct for their process improvement project in Smarter Solutions’ Lean Six Sigma workshops (reference chapter 15 of Integrated Enterprise Excellence Volume III – Improvement Project Execution: A Management and Black Belt Guide for Going Beyond Lean Six Sigma and the Balanced Scorecard).
In this evaluation, I took a large sample of pool water from which smaller amounts were drawn for each store that was to conduct the tests. I also did an evaluation of the water with a neighboring couple who also had a pool; i.e., Neighbor 1, Neighbor 2 and me (Forrest). The results from this assessment are shown below, where Neighbor 1, Neighbor 2, and I agreed to the reported Taylor-kit test reading (far right in the table). I should note that this study does not consider that someone else in any given store could report a different number for each measurement.
From this test, it was concluded that any individual reported test result could lead to a very different course of action than what might be suggested from another supply-house. With this type of evaluation, it is not unusual to also observe several other issues.
A few things I noted when conducting the evaluation were:
- There can be differences between recommended levels of a characteristic/chemical, which is dependent upon the company/store/individual that is utilized for the test.
- One Leslie’s store employee ran out of water when conducting the test. This was not an issue with me since I just gave him more water from my supply; however, one could conclude that Leslie’s stores should increase their container size; e.g., the size of Warehouse pools.
- Both Leslie’s stores’ employees who conducted the test had difficulty and complained about the company’s database for entering and storing information about the pools reported metrics. Leslie’s also does not have an overall unified computer system between stores; i.e., for each store one will need to repeat both their personal and pool information.
- I noted at one store that they were using a similar test kit to mine for evaluating phosphates. I remember that the instructions indicated that a specific time was for mixing and idle time before evaluation. It did not seem to me that the person who did the test followed these times for conducting the test, which could affect the reported measurement.
With the above described form of testing, one does not really know what the “correct response” is for any given test, especially cyanuric acid, which interests me the most. One thing that can be noted is that the store that I had been using for my chemical test is reporting cyanic acid levels at a level that is much higher than what other stores and my Taylor kit indicates; hence, I am concluding that the store’s reported number is higher than the actual pool’s cyanuric acid level.
With the above described form of testing, one does not really know the “correct response” for any given test, especially cyanuric acid, which interests me the most. One thing I do feel confident in is that the store that I had been using for my chemical test is reporting cyanic acid levels at a level that is much higher than what other stores and my Taylor kit indicate.
From this evaluation, I have decided to use the Taylor kits regularly for making my pool-chemical adjustments and not take samples to any pool supply store, since I now don’t have faith in the accuracy of the pool-supplier’s reported metrics.
Now that a consistent measurement approach has been determined, I will next work on determining the best process for maintaining good pool chemistry. With this effort, focus will be given to avoid any algae problems and the elimination of periodically draining a portion of the pool and then refilling for the purpose of removing cyanuric acid that was added from the chlorine tablets. The reason for giving focus to avoiding periodic pool draining is not only the cost of water but in central Texas water is a valuable commodity. I want to do my part in conserving this resource as much as possible.
When our pool’s cyanuric acid reaches an ideal state from the chlorine tablets, one hypothesis that I will be test is stopping usage of chlorine tablets and switch only to the application of liquid chlorine at dusk. My rationale for this is that I have read that:
- The ideal state for cyanuric acid increases how long chlorine remains in the water by five times.
- Chlorine is depleted by sunlight; hence, it is best to add liquid chlorine at dusk.
The use of data with a consistent measurement system will provide the guidance to whether this newly considered process will be effective or not.
I feel optimistic that liquid chlorine may only need to be added to the pool once (or maybe twice) per week. Time and good measurement data will be able to show whether this hypothesis appears valid or not.
