Pool Chlorine Options

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Pool Chlorine Compositions.

There are four primary chemical compositions of chlorine that are used to sanitize swimming pools. Each will work to help keep your pool water where you want it: clean, clear, and free of bacteria. However, knowing which to use and when to use it is important. And so, let’s take a look at your options.

Trichloro Triazinetrione. (Trichlor)

This is probably the most popular chlorine option in this region. Available in one-inch or three-inch tablets, there are lots of pluses to trichlor. Firstly, it is slow dissolving so there isn’t the need to add it daily. Secondly, count on it to also contain cyanuric acid (CYA). Better known as pool stabilizer or pool conditioner, this adds life to chlorine by minimizing the effects of ultraviolet light. UV rays burn chlorine out of the water and the hotter and brighter the sun, the worse the burn-out. CYA helps minimize the effect. The only drawback is CYA does not naturally dissipate. Too much CYA can reduce chlorine’s effectiveness, but pumping out some water and replacing it with fresh solves the problem.

Are there any real negatives to trichlor? Not really, aside from the possibility of increasing CYA amounts to an unwanted level. That’s easy to fix, as mentioned above. Trichlor is highly acidic so keep an eye on the pH and adjust to the proper range, if needed. Some trichlor contain sodium tetraborate, which helps stabilize pH. Check the chemical analysis on the product label.

Sodium Hypochlorite. (Pool shock)

Shock is a very important chemical in pool water maintenance. It adds an immediate boost to the chlorine level but serves two other major purposes. One, it has a high pH, which is great if you use trichlor as your primary sanitizer. The two offset each other rather nicely and make it easier to balance the water. Unfortunately, some pool owners use shock daily as their primary sanitizer. Have fun keeping that water balanced! Two, shock helps clear chloramines from the pool. When solid chlorine in the water is spent, the molecules attach themselves to dead organic contaminants. They can produce a strong chlorine or ammonia-like odor. This can give a false sense of security that the chlorine level is acceptable. It’s not. Shock oxidizes chloramines and allows your free chlorine level (good chlorine!) to do its job.

Note that pool shock and bleach are similar, with one major difference. Pool shock is much stronger and significantly more effective. Laundry bleach is usually a 3% to 5% solution, and if it’s been on the shelf long, probably even less. On the other hand, pool shock is considerably stronger at a norm of 10%. Here’s the kicker: Sodium Hypochlorite is very gaseous and dissipates quickly, both in storage and in the pool. Shopping for hamburger and eggs at a grocery store recently, I came across a palette of pool shock. Production dates were stamped on the boxes. Some were only 10-days old. That’s good! Unfortunately, they had been stacked on top of many cases stamped three months prior. That’s bad! Shock loses strength at a rate of 25% to 30% every month. You want fresh, otherwise you’re paying a pretty penny for the equivalent of weak laundry bleach.

Calcium Hypochlorite. (Cal Hypo)

Cal Hypo is an un-stabilized chlorine sanitizer that contains calcium, used primarily as a filler. Available in both granular and tablet form, cal hypo has been around for many years but one thing is consistent. The active ingredient is less than virtually all trichlors found on shelves. Available chlorine levels usually fall in the 50% to 55% range, although on rare occasions, possibly a little higher. The one constant is that users are constantly elevating the calcium level in their water. Eventually, the water can become so saturated with calcium that it comes out of solution. Water clouds up and calcium attaches to the surface. Brush up against the side and it will feel like sandpaper.

It does have its place in pool ownership, though. Used properly, cal hypo can be very beneficial. One example is its role in the Simple Salt sanitization system for above ground pools. This is an extremely low chlorine system that relies on minerals and copper to kill bacteria and sanitize the water. Here, a specialized shock raises the dissolved solids level, which facilitates transference of the copper and minerals throughout the water. The result is pool water that feels good to swim in, is low maintenance, and looks great.

Di-Chloro Triazinetrione. (Dichlor)

Have an indoor pool? This sanitizer is great. It is sodium based and is more pH-balanced than trichlor. Many outdoor pool owners choose to use it also, and it does have stabilizer added. Usually found in granular form, it dissolves quickly and much easier than most cal hypo granular products.

Lithium Hypochlorite

I bring this up in passing only because you may have a friend or relative that remembers it from years ago. Forget it ever existed, because for swimming pools, it no longer does. With a growing need for lithium in the rechargeable battery industry-wide wave, it’s no longer available. It was already the most expensive chlorine pool sanitizer out there, even before the eco-battery deluge.

In short…

We’re into summer now, and it’s imperative you keep an eye on your chlorine levels. Remember that for every 10-degrees of water temperature rise, you need approximately 25% more chlorine in your water. Pick the type you’re comfortable with but understand the differences in types, strengths, and freshness. If local, I recommend a visit to Eastgate Pools & Spas. We offer a great selection of quality, professional-grade chlorines, and related chemicals. Plus, our water testing experts can guide you through any issues you might be having. Perhaps more importantly, with their knowledge and recommendations, they can head off problems before they occur.