acid is recorded as parts ….
acid is recorded as parts per million.
Low cyanuric acid concentrations will give fine particles, making a hazy solution, while high cyanuric acid concentrations will produce larger particles.
This test is temperature dependant, so it should be attempted at temperatures of about 75 °F. Low temperatures, below 60 °F can result in a false high reading as much as 15 ppm. Meanwhile, high temperatures, above 90 °F can give false low results
If borates are used, it will be necessary to test for them about once a month. Over time, water loss from backwashing and splash outs – but not evaporation – will lower the borate levels.
Borate positively contributes to water clarity and a silky feel, and they also buffer the pH from rising. They do this best at a concentration of about 50 ppm. When the borate level goes lower than about 30, pool operators may decide to add more.
Test strips are available from a variety of manufacturers to get a read on borate levels.
Calcium hardness a measure of the calcium concentration of the water, expressed as ppm calcium carbonate. It affects both the clarity of the water, as well as whether or not the water will be scale forming or corrosive to surfaces.
The ideal range for calcium is recommended to be within 150 to 250 ppm, although the acceptable range extends to 1,000 ppm.
Experts recommend a lower level (100 to 800) for spas because hot water promotes scale.
Testing calcium hardness should be conducted monthly. It is usually tested by titration.
A buffer and indicator reagent are added to a sample of water, and the solution is swirled to mix. The solution will turn red in the presence of calcium compounds. Next, a calcium hardness reagent (EDTA) is added, and every drop is counted as the solution is swirled. When the solution turns blue, the endpoint has been reached. The number of drops is then multiplied by an equivalence factor, and recorded in parts per million calcium carbonate.
Sometimes, the solution will turn purple rather than blue at the endpoint. This is due to metal ion interference. The metal, usually copper from copper based algaecides, causes this purple endpoint. Manufacturers recommend re-doing the test and adding the hardness reagent to the test prior to adding the first reagent.
Total dissolved solids
Salt and total dissolved solids are both tested using conductivity meters, which measure the conductivity of the water from conductive ions such as sodium, chloride, calcium, magnesium, sulfate and others.
Water is more or less conductive because of the dissolved ions in the water. Ions that conduct electricity are called electrolytes. For example, salt is an electrolyte. TDS and salt meters measure the conductivity of water due to these electrolytes. Not all dissolved solids are electrolytes and therefore do not register on a TDS meter. For this reason, the TDS meter is really only an estimate of the true TDS. The true TDS is higher.
By the same token, not all electrolytes are in salt water chlorine generated pools are sodium chloride, and salt readings may test higher than they should.
Conductivity meters can give inaccurate results if they are not clean. Don’t allow fingerprints or other residues to remain on the probe. Clean and store the probe according to manufacturer’s directions.
While not an aspect of water balance, high levels of phosphates can certainly contribute to algae, which is something paying customers will not tolerate from a pool service technician. Especially at high cyanuric acid levels, phosphates allow algae to grow because they provide an essential nutrient. This can occur even when the chlorine is in what might be considered an acceptable range. That’s why it’s a good idea to keep phosphates as low as possible, and definitely under 500 ppb.
Test strip and powder packets are available to get an idea of phosphate levels that are simple to use. With the powder packet, just add the reagent to a fixed volume of water and invert the tube for a minute before comparing the color to a chart provided.
With the test strips, the strip is bent and placed in the lid of a vial of water. The tube is inverted five times and the color compared a provided color chart.