Using the Correct Tablet for your pool & spa applications.
Some pool operators prefer the use of tablet chlorination over liquid chemicals,  finding them less bulky and safer to use. But there are many different types of tablets available. Here we will examine the positive and negative aspects of the two most common types in order to help you select the proper tablet for the application: they are Trichlor and Calcium Hypochlorite.
Trichlor tablets are normally 3” in diameter (200 Grams) and come in a 25 or 50 lb pail.Trichlor is 90% active chlorine on the label, but in fact it consists of 55% cyanuric acid (see below). The tablets may or may not come individually wrapped in plastic to avoid degradation and odors while in transit and storage. They are normally used in a simple flow through feeder, and the chlorination rates depend on the number of tablets in the feeder, and the amount of flow through the feeder.
Trichlor tablets can have negative effects on the pool water chemistry if it is  not watched very closely. First, it has a pH of 2.8, which is 30,000 times more acidic than the desired pool/spa pH level of 7.5. In fact for every pound used (per 10,000 gallons) one must add over 1/4 lb of Soda Ash to the pool water in order to neutralize the pH effect from Trichlor.  Second, Trichlor feed system is an alkalinity scavenger, meaning that it consumes total alkalinity  thus requiring the addition of Sodium Bicarbonate to raise the alkalinity to an acceptable level of 80-120 PPM. Since most pool water supplies are already low in alkalinity, the use of Trichlor will increase the attention to detail and the cost of operating any commercial pool. Finally, Trichlor will continually raise the Stabilizer level in the pool or spa. For each 50-lb pail of Trichlor used, the stabilizer level in a 50,000 gallon pool will be raised by 60 PPM. According to many major sources, stabilizer levels should be maintained between 20-30 PPM. New research provides definitive proof that high stabilizer levels contribute to accelerated pool finish degradation and algae. Department of Health (DOH) codes also limit the amount of stabilizer in commercial pools (100 PPM) and spas (40 PPM). Trichlor feeders are no longer allowed in spas per newer DOH codes.
Another negative of Trichlor is that the feed rate of the tablet chlorinator is limited by the actual (slow) dissolving rate of the Trichlor tablets, as they were designed to last an entire week in a residential floater or skimmer. Slow dissolving rates make it very difficult to get the tablets to keep up with today’s hectic pool operations. Also, Trichlor tablets have been linked to blue-green staining of pool surfaces. This is partly due to heavy corrosion of copper components (heaters) caused by the low pH effect of the Trichlor tablets. The released copper combines with pool sulphates to form copper sulphates, which may result in a blue-green stain.
Pulsar Calcium Hypo tablets are manufactured in a small 1.25” x .75” rounded “pillow shaped” briquette. It consists of  approximately 65% available chlorine and come in 50 LB pails. The tablet contains several key ingredients which are vital to the proper water balance of a swimming pool or spa. Calcium: since most pool “fill” water is softened (calcium hardness is removed), it is lacking in this key ingredient. City water normally contains 100-120 PPM of calcium hardness, while proper Langelier and Ryznar water balance dictates a calcium hardness level of 350 PPM or above.  Alkalinity: unlike the Alkalinity-scavenging characteristics of Trichlor, the Pulsar briquettes actually have a mild alkalinity-increasing effect on the pool water. Alkalinity and Calcium are key water balance components and are an integral byproduct of Pulsar chlorination. Pulsar briquettes also contain a corrosion inhibitor that helps protect the pool components. Additionally, the feed system is also documented to help remove metals out of the pool water.
Pulsar briquettes are considerably more pH-neutral than Trichlor or liquid Bleach. Field studies confirm that 50 lbs of briquettes only require 1 gallon of muriatic acid to offset the pH influence of the briquettes. By comparison, bleach would require between 2.5-5 gallons of acid to accomplish the same neutralization. The Pulsar feeder system, along with the RAPID dissolving rate of the briquettes, combine for quick recovery, and can keep pace with even the heaviest bather loads. The Pulsar feed system also has been designed to continually SHOCK-TREAT the pool water thus helping reduce chlorine odors and irritation-causing chloramines.
Therefore, the biggest difference  between these two different types of tablet systems is what is included and what is not......
To summarize, the Trichlor system, which many feel is much better suited for residential applications, provides: low pH, high stabilizer, slow dissolve, no calcium, reduction of alkalinity, higher potential to stain, and (with overstabilization) higher potentials for algae, and pool finish degradation.
The Pulsar system, which was developed specifically for commercial applications, provides: more neutral pH, no stabilizer, quick dissolve, calcium increase, mild alkalinity increase, removes metals, continual shock treatment, corrosion inhibitor, and does it all with one convenient tablet.
Saturday, June 30, 2007
Which Tablet
is right for
your pool
Due to nationwide regulations regarding sodium hypochlorite delivery and storage issues, tablet feeders are more popular than ever.
However, each and every chemical compound has well-documented positives and negatives. To properly investigate the best tablet for your particular application, one must look
at incoming water composition, bather load,
chemical pricing, pH costs, and more.
Read on.....