Chlorine is Chlorine, right? To the uninformed yes, but to educated pool owners like yourself, you know that there are many types of chlorine. Each type of chlorine has it's own specific purpose and benefit. There are types of pool chlorine used for everyday chlorination and chlorine used for super-chlorination or shocking of the pool. We have chlorine made specifically for vinyl liners, chlorine that is stabilized and chlorine that is pressed into different tablet sizes - for different sizes of swimming pools.
Different chlorine types are extremely incompatible with each other. Do Not Mix different chlorine types!
Chlorine for Everyday Chlorination
Chlorine Tablets and Sticks
For everyday chlorination, we want to use a type of chlorine that is slow dissolving and slow reacting. The best chlorine to use for everyday chlorination are tablets or sticks. Our best selling chlorine product is our Jumbo 3 inch tabs chlorine tablets.You'll find that these offer the best value in pool chlorine tablets, pound for pound. These tablets are known as TriChlor, short for Trichloro-S-Triazinetrione. Pressed into tablet or stick form, they are easy and safe to store and handle. Just drop enough tablets into your chlorine floater or automatic chlorinator, to raise the chlorine level in the pool above 1.0ppm.
Chlorine tablets can also be purchased in 1 inch tabs. These are suitable for chlorinating small pools or spas. Another benefit is that 1" tabs dissolve slightly more rapidly than 3" tabs, due to their increased surface area. This can be beneficial when the chlorine level needs to be brought up rapidly.
Chlorine sticks are made with the same recipe used for 3" and 1" tablets, they are just pressed into a different shape. For some chlorinator styles, the stick form seems to fit better, filling the chamber more fully. Chlorine sticks are also larger than tablets; this may mean fewer trips to refill the chlorinator. Other than that, sticks and tablets are essentially the same.
Larger commercial pools can use chlorine tablets, in large chlorine feeders, but many larger pools find an economic advantage to using Liquid Chlorine. Sodium Hypochlorite, a 12.5% solution of Bleach, is delivered to large pools by truck, and pumped into 50 gallon vats. This super-bleach (about 2.5x stronger than Clorox), is pumped directly into the pool return line, using a chlorine metering pump. The chlorine pump allows the pool operator to set the speed of pumping, trickling an ounce or two per minute.
Liquid chlorine does have it's drawbacks however. It's not stabilized, like tablets are, so even more Cyanuric Acid will be needed to shield the chlorine from the sun. Secondly, liquid chlorine has a very high pH level, close to 13 - which requires users to keep a lot of acid on hand, to lower the pH level as needed. It's not very well suited for use on residential pools, due to it's limited availability in most parts of the country. The delivery trucks won't come out to bring you just 5 gallons, and it can be hazardous to store on site anyway.
Florida, is somewhat of a peculiar market in the pool business, they do most things a little bit differently. In Florida, it's common to use liquid chlorine as the primary sanitizer, and many pool stores will have a stock of liquid chlorine, sold in a case of 4x1 gallon. However, unless you are using a metering pump, it's a bit awkward to use. Pouring bleach into a pool will raise the chlorine level rapidly, followed by a steady decline. It's much better to have a slow, steady introduction of chlorine, than to have peaks and valleys of chlorination.
New to SPP is our Instant Liquid Chlorine (Just add Water!). It's too dangerous to ship liquid chlorine around the country, but our product engineers have found a way to overcome the challenge! Instant Liquid Chlorine is convenient to ship and use, and just like Liquid Chlorine, is sold in a 4x1 gal pack.
Chlorine for Super Chlorination
Super Chlorinating, in my book, is raising the chlorine level quickly, but not as high as when doing a "pool shock". Shocking the pool is a periodic treatment to oxidize micro-contaminants in the pool water. Our everyday chlorination will kill most pathogens, but chlorine molecules can be rendered inactive when they combine with nitrogen or ammonia. This creates what is called Chloramines. Chloramines are no longer effective sanitizers, and they are the cause of red eyes and a strong chlorine smell.
Shocking the pool, or increasing the chlorine level quickly, to a threshold known as breakpoint chlorination, disrupts the cell membranes of everything organic in the pool, and breaks apart the chloramine bond. I like to envision a lightening bolt ripping through the water, "shocking" everything in sight. Like an underwater atom bomb, it's very destructive, on a molecular level.
For shocking a pool, we need a chlorine that is fact dissolving and fast acting - the opposite of our everyday chlorinating tablets. Granular chlorine is the most common method, most commonly sold in 1 pound bags. Liquid chlorine can also make a great shocking chlorine. When shocking the pool, follow label instructions, with the goal of adding enough chlorine to reach "Breakpoint Chlorination". If this threshold is not reached (somewhere around 30ppm), full oxidation will not occur, and the full benefit of shocking the pool will be missed, and you will have only Super Chlorinated the water.
The most economical pool shock is known as Cal Hypo (Calcium Hypochlorite). A stabilized form of pool shock (pressed with CYA) is available in a granular chlorine known as DiChlor (Dichloro-S-Triazinetrione), for a longer lasting granular compound that will stay around for a few days, instead of burning off immediately.
Vinyl liner pools should always pre-dissolve pool shock before adding to the pool, to prevent bleaching the liner - or use a Non-Chlorine pool shock, or Lithium pool shock, both of which dissolve immediately upon contact with your pool water.
Pool shocks are available in different strengths; brewed stronger, if you will, with a higher level of available chlorine. Our Strongest pool shock has 73% available chlorine, and will have a greater effect, whether you are trying to remove chloramines or remove algae and bacteria.
Granular chlorine can be dangerous if allowed to mix with other compounds or chemicals - including soda pop, antifreeze, algaecide, dirt, leaves. Fast and explosive reactions can occur, with a strong and violent fire that is almost impossible to extinguish. Store and handle with care!
Chlorine Buying Guide: Look to the Label!
- Percentage of Available Chlorine. Trichlor tablets or sticks can be as high as 90% available chlorine, and liquid chlorine can be as low as 10% available. What this means is that pound for pound, the 90% available chlorine has more chlorine creating potential than the 10%, 9 times more, to be exact. Compare the cost per pound for similar or different chlorine types to make the best comparison.
- Stabilized Chlorine. When you see the word "Stabilized" on the label or in the name, this means that the chlorine has an additive known as Cyanuric Acid. CYA, as I call it, protects chlorine from the sun by attaching itself to the chlorine molecule, forming something of a molecular umbrella, shielding it from ultraviolet rays.
- Active Ingredient. There's all sorts of fancy brands, with hard-hitting names like Sock-It and Burn-Out. If you look at the label, on the lower left, you'll see a line listing the Active Ingredient. Compare apples to apples in this way, and the numerous options available to you will make more sense.
So, now you know, Chlorine is Not Chlorine ~ so many types are available that it's easy to become confused. Choose a tablet and a granular for your pool, and be sure to follow the label instructions. If you have any questions about pool chlorine, post a question below, or give us a ring at 800-983-7665 - we love to "Talk Chlorine"!
SPP Pool Enthusiast