-are composite tablets containing the Chlorine (as Trichlor) that you need to keep the pool sanitized - plus a few added extras. They are also known as Multi-Function Tablets
Each manufacturer has their own formula for the mix of compounds in their product and, according to the blurb on the container, the extras may include Chlorine Stabiliser (as Cyanuric Acid), a Flocculant a (as Aluminium Sulphate) , an Algaestat, a Fungistat, a Bacteristat, Copper Sulphate, pH-reducer (as Sodium Bisulphate) and various other chemicals, (like perhaps a sprinkling of Tinkerbelle's Patent Fairy Dust?)
And they very possibly do; but is that a good thing? In our opinion it's a bad thing and here's why
To keep the pool sanitized we need to add Chlorine - this is not in dispute. What is in dispute is whether all the other added chemicals are going to be good for the pool or bad for the pool
Look at it this way; if the tablet contains more than just Chlorine it's clearly not pure Chlorine, so it will not raise Chlorine levels by as much as a pure Trichloro product
Any other chemicals included in the mix add to the Total Dissolved Solids, cause a build-up of undesirables and bring forward the time at which you need to partially or completely drain the pool and refill it with fresh water
Chlorine is added to a pool to keep it sanitized and if the Chlorine donor is Triclor or Dichlor there is no need for added Cyanuric Acid because in water that is kept at the ideal of pH 7.4, or close to it, the Chlorine will produce Hypochlorous Acid (sanitizer) AND Cyanuric Acid (stabilizer) in the correct proportions
Moving on to the Flocculant part of the tablet:- why would you need a Flocculant if the pool is healthy and the water is clear?
Copper Sulphate is a very good preventative treatment for Algae but it has one major drawback inasmuch as it never leaves the pool other that by partial dilution when a filter is back-washed and the pool is then topped up with fresh water
So the concentration of Copper Sulphate rises inexorably and eventually reaches the point where it will stain plaster and grout, and turn hair and nails a blue-ish green. The blue spots in the tablet shown above are Copper Sulphate; scattered throughout like raisins in a bun
Trichloro produces Hypochlorous Acid when dissolved in water, as mentioned above. Hypochlorous Acid IS, amongst other things an Algaestat, a Fungistat and a Bacteristat. So you don't need an extra dose of an Algaestat, Fungistat or Bacteristat
Follow the 'most economic' routine below and you won't go far wrong: -
Maintain a Chlorine level of 1-3ppm and never let it drop below 1ppm
Keep pH between 7.2 and 7.6 but strive for the ideal of 7.4 pH
Superchlorinate every 2 weeks at dusk with Sodium Hypochlorite - a very inexpensive chemical
Add Copper Sulphate no more frequently than twice a year
Use a Flocculant only when it's needed (or use Jolly Gel at any time)
PS - It's very unlikely that Multi-action tablets contain Fairy Dust, or even that such a substance exists; the manufacturers would just like you to think it does. Like most businesses they'll happily sell you things you don't need all day long!
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