The topic of the day came from a pool owner named Jeff, having trouble with the build-up of cyanuric acid levels in his pool. Jeff wanted to know about chlorine that was not stabilized, not our beloved 3″ chlorine tablets and sticks, but chlorine that does not contain cyanuric acid, also known asstabilizer or conditioner.
For every chlorine tablet that dissolves in your pool, a small amount of cyanuric acid also dissolves into the pool water. For most pools with adequate rain, backwashing and winter pump down, it won’t build-up to a high level. However in pools that are covered, indoors or with cartridge filters, and in dry regions with little rainfall, cyanuric acid levels can rise too high, too fast.
And when the cyanuric acid level creeps up too high, in the 80-120 ppm range, it can be hard to maintain a good chlorine level, and the killing power of chlorine is suppressed. So pool owners like Jeff are told to reduce the cyanuric acid level, by draining and refilling the pool.Bio-Activecan also be effective in many cases but not all, to lower cyanuric acid levels in pools.
Here’s some other alternatives to replacing the water, or treating with a remover.
Non-Stabilized Chlorine Options to Trichlor Tablets
1. Liquid Chlorine
Regular bleach, or sodium hypochlorite – contains no cyanuric acid. Household bleach is normally a 5% or 6% strength, while commercial strength bleach for pools is generally 12.5% strength, and delivered by truck and hose. You could add liquid chlorine from a gallon bottle every day, but to avoid peaks and valleys in chlorination, use aChemical Metering Pumpto inject the liquid chlorine directly into the return line, slowly throughout the day. You could use a gallon bottle, but a 5-gal or 15-gal drum (or the 55 gal Vat) is more convenient, set on the ground below a wall-mountedliquid chlorine pump, which pulls the bleach out of the container and pushes it into the return line via hose injection fitting. Chemical pumps are adjustable, in seconds of run time per minute, turning on/off to maintain the setting, but they are constant run. A plug-in timer can be used, if you don’t run your filter 24/7. Requires care with the handling and storage of bleach, and the very high pH which will require frequent additions ofpH decreaser. Pumps and hoses also require some measure of upkeep, or repairs to hoses and fittings.
2. Salt Chlorinator
Salt Chlorinators, aka salt chlorine generator will create most of the chlorine needed for your pool. Add several hundreds pounds of purepool salt, and plug-in the controller and salt cell to make the magic. The salt cell will create chlorine instantly in the pipe from plain old salt + h2o, and after the chlorine is spent, it reverts back to salt + h2o again. Salt Cells need some repair or replacement parts every 3-5 years, but in the long run a salt system can cost around the same as the cost of using tablets. But of course, like using liquid chlorine, no stabilizer is added to the chlorine that your salt system creates, although maintaining a 20-40 ppm CYA level is recommended for most outdoor pools. People also like the ease of use of a salt system, and the soft silky feel of the water. The main downside to a saltwater pool is the initial cost of thesalt water systems, and the 5 yr (+/-) life on salt cells, sensors, circuit boards and such. But the chlorine, that’s hands free and easy to control with push button simplicity.
3. Cal Hypo Tablets
Tablets made out of calcium hypochlorite, a similar formula to the cal hypo pool shock that we sell, but pressed into 1″ tablets.Cal hypo tabletscannot be usedin a regular 3″ Trichlor tablet feeder, because they dissolve too rapidly. Cal Hypo feeders are used to spray individual tablets with water, slowly one at a time, to release the non-stabilized chlorine into the return line. Like Cal Hypo shock, Cal Hypo tablets areunstabilized chlorine tablets, containing no cyanuric acid. Cal Hypo tablets are more expensive than regular tablets to buy, and the specialized feeders required to use them are also on the pricey side. For pools in hard water areas, Cal Hypo tablets will add calcium to the water, in about the same amount as Trichlor tablets add cyanuric to the water – so you may be trading one problem for another.
4. Go Low Chlorine
There is a fourth method or alternative practice, which may work for some, and that is to reduce the amount of stabilized chlorine tablets used, by reducing the chlorine demand. This can be done by augmenting or supplementing your chlorine with aNature2 ExpressorFrog Mineral system, along with regularpool shocktreatments, good water balance and good filtration practices. With Minerals, you can use 50% fewer tablets, just enough to produce a low 0.5 ppm level of free chlorine. Most people cut their chlorine tablet usage in half when using a mineral purifier! For example, if your pool uses 4-6 tablets per week, you will only need 2-3 tabs per week, which slows the build-up of cyanuric acid by 50% – which can be enough to alleviate the problem for some pool owners.
5. Go Tablet Free
Take the fourth method above, and add another alternative sanitizer likeOzone or UV purifiersto the mix, and you can stop using chlorine tablets altogether. When you add the 1-2 punch of aMineral System + Ozone or UVSystems – you don’t need to use any tablets at all. It’s true – any clean pool with good water balance and a large effective pool filter, with regular shocking (either non-chlorine or chlorine shock), can use aMinerals + Ozone, or Minerals + UV combination to replace the need for stabilized chlorine tablets. Additional helper chemicals like Clarifiers or Algaecides or Enzymes can also be employed if needed.
Trichlor vs. Cal Hypo
For pool chlorination, there are two main types of chlorine – hypochlorites or isocyanurates. Calcium Hypochlorite (Cal Hypo) and Sodium Hypochlorite (Bleach) are the former, and Trichlor tablets and Dichlor shock make up the latter.
All types of pool chlorine produce hypochlorous acid, the killing form of chlorine, but all have different “side effects” to their use.
- 10 ppm FC from Trichlor raises Cyanuric Acid (CYA) by 6 ppm.
- 10 ppm FC from Dichlor raises CYA by 9 ppm.
- 10 ppm FC from Cal-Hypo raises Calcium Hardness (CH) by 7 ppm.
- 10 ppm FC from Sodium Hypo raises Salt levels by 17 ppm.
SODIUM HYPO vs. CAL HYPO vs. TRICHLOR
Sodium Hypo (liquid chlorine) is a popular choice where available, however due to the very high pH (13) of liquid chlorine, a gallon of acid is required for every 10 gallons of bleach used, and maintaining constant pH and alkalinity levels can become difficult. Liquid chlorine systems also require a safe space for large chlorine vats, and close access for a bleach delivery truck.
Cal Hypo (granular or tablets) are another choice for large pools with high chlorine demand. Granular has a fairly high level of pH (11), but tablets are lower (9). It won’t contribute to cyanuric acid or salt levels (sodium), but it does increase calcium hardness levels in the pool, which could be undesirable for hard water areas. The tablet form may also come mixed with additives to help clarify the water or reduce stain and scale formation.
Trichlor (3″ tablets or sticks) are not usually used for large commercial pools, as they don’t dissolve fast enough to meet the chlorine demand, but are more suited to pools under 50,000 gallons. Being stabilized, Trichlor tablets will build up cyanuric acid in pools over time, requiring periodic additions of fresh water. Having a very low pH level, Trichlor tablets depress the pool water pH and alkalinity levels, requiring frequent additions of pH increaser.
POOL CHLORINE DELIVERY SYSTEMS
Sodium Hypo (liquid chlorine) is delivered via trucks that also supply dry cleaners and industrial users of bleach, and pumped into 50 gallon vats. For smaller pools, liquid chlorine can be hand fed daily, or 5 gallon drums can be used. Chemical pumps are used to pump from the chlorine vat or drum into an injection fitting placed into the return pipe, and have a dial to control the chlorine flow amount.
Cal Hypo granular is used by either manually broadcasting or dissolving into water and pouring into the pool, or it can be used with a granular cal hypo feeder. Cal Hypo is also made in pellets and pucks, or tablets of various sizes, designed to be used in very specific feeders, usually made by the tablet manufacturer, although they could be used in floaters, or floating chlorinators. Most cal hypo feeders like theAccu-Tab or the Pulsar are expensive and complicated items, with exception to the CCH feeder, shown here, or the new CCH Endurance feeder and Endurance cal hypo tablets.
Trichlor tablets are used in a typical residential chlorinator, installed onto a return line, holding up to 9 lbs of tablets, and can also be used in a chlorine floater. Dichlor can be dispensed in a granular feeder made specifically for Dichlor, such as the Watermatic dichlor feeder, and although more pH balanced, is one of the most costly feeders and types of chlorine to use. In many pools, build-up of cyanuric acid is a concern as it reduces the efficacy of chlorine and requires periodic draining and refill with fresh, unstabilized water.
Cal Hypo tablets may make sense for you if you operate an indoor pool, or a not too large outdoor pool with problems with cyanuric acid levels rising too fast, and you don’t have extremely hard water in your area.
There you have it Jeff – 3 types of “unstabilized chlorine” or chlorine without cyanuric acid, and 2 alternative practices that can be used to help the problem with cyanuric acid build-up in pools. All of these methods are tried and true, and can be safely and effectively used in most residential inground pools, with good filter systems.
Some are more convenient than others, and all have a significant initial cost to switch over to using non-stabilized chlorine. I hope this helps those who struggle with high cyanuric acid levels.
