Epic Pools

What are the benefits of draining my pool?

Sometimes customers have asked us “If a pool is not green and doesn’t need to be acid washed or repaired… then why drain it?”

It is often beneficial to change part or all of the water in a swimming pool after 3-5 years. The benefits could be summarized as an improvement in water “health”. The water in a pool gets a slow buildup of a number of materials over time with regular maintenance including Cyanuric Acid (CYA) or Stabilizer and Calcium. The rest are generally summarized as Total Dissolved Solids or “TDS”.

TDS

Since an outdoor pool is an open system there are always pollen, dust, dirt and debris (and people) getting into the water. While the large pieces of debris are typically cleaned out, and smaller pieces are often oxidized or broken down by Chlorine and filtered out, there are still minerals and other additives too tiny for a pool filter to remove. This remaining material is referred to as “TDS” (Total Dissolved Solids).

When filling an empty pool we have generally found that TDS can be anywhere from 50 to 300ppm (parts per million) right out of the tap. After adding water from the tap, we then add 200-300ppm of calcium and at least 3000ppm of salt if a pool has a salt cell for chlorine generation. So fresh pool water will typically have a TDS of 250-600ppm right away if it is a regular Chlorine pool or 3250-3650ppm if it is Saltwater pool after adding 3000ppm of salt.

Summer temperatures can reach 115 degrees or more here in Arizona, sometimes for days or weeks at a time. Combined with periods of lower humidity and windy conditions the evaporation rate in a swimming pool can speed up greatly. When water evaporates, only the H2O dissipates and the TDS will remain in the water. The pool water is replenished with fresh water supply typically through either a hose or the automatic water fill. Since the water coming into the pool has a TDS factor of 50-300 it causes a rise in TDS over time.

In addition to the TDS from tap water, everything that gets in a pool has a TDS factor (or ads to the TDS). So the weather and usage will create higher and higher TDS levels over time.

When the TDS level of pool water rises to 1500-2000ppm or more BEYOND THE AMOUNT ACCOUNTED FOR AS SALT a pool owner will start to have subtle problems that begin to show up over time. These can include calcium deposits on pool at water line, discoloration of plaster, brown manganese or copper stains, a salty (or saltier) taste to water, and a harshness to the water that causes irritation to skin and eyes etc. If not addressed, as the TDS rises higher and higher, these problems will build to a point where the pool surfaces will begin to deteriorate. Note: Remember to subtract out the salt level from the TDS number for saltwater pools so the salt is not included in your TDS count.

Sometimes if the TDS level contains minerals they can precipitate as stains very suddenly if a pool is shocked or super chlorinated. This is because super chlorination raises the pH very quickly. When the pH rises the water can go out of balance temporarily and be unable to hold the metals in solution.

Leaking filter?


Sand filter tanks rarely leak themselves, however leaks often occur in and around the multiport interface. A common complaint is that water is leaking out of the backwash port of the multiport (six position) valve. Slight adjustments of the handle may temporarily solve this problem. A more permanent repair may necessitate replacement of the spider gasket inside of the multiport. You may also have leakage up around the middle of the handle on the valve, which external adjustments rarely fix. This usually requires replacement of a Teflon washer and sometimes the spring as well.



You may have a push-pull valve, or slide valve as it is sometimes called, instead of a multiport valve. Leaks can occur through the top of the index plate, or out of the backwash line. This is a easy inspection to determine what o-rings need to be replaced. Leaks can also occur at the bulkhead unions where the valve attaches to the side of the filter, or around the threads on a top-mounted multiport. The drain plug can leak if not secured tightly or properly sealed.