- Why has my pool gone green when my test kit says the chlorine level is OK?
Your chlorine is 'locked in' by the chemicals used to stabilize it. Granular and tablet form chlorine is bonded to cyanuric acid to prevent it from being burnt off by the sun too quickly. But whilst the chlorine will be used up, the cyanuric acid will remain. Too much cyanuric acid in your pool over stabilizes your chlorine and it cant get free to attack bacteria and algae.
You will have to throw out some of the water with the cyanuric acid and replace it with fresh water. Regular and thorough back washing of your filter should prevent
over stabilization but in a heavily used pool up to 5%, maybe more, of your water should be replaced each week to keep over stabilization at bay.
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- Swimmers complain of sore eyes and a chlorine smell. They say there is too much chlorine but my test says my chlorine level is about
right at 1.5ppm. What's wrong?
There is probably not enough chlorine. Under normal circumstances chlorine breaks up organic material to harmless, un-noticed
nitrogen and salts. But if the chlorine level is low or the organic material level is high the chlorine slows down its work rate and produces instead Nitrogen Trichloride.
This is a type of tear gas, hence the sore eyes. The swimmers are not smelling chlorine they are smelling the Nitrogen Trichoride and mistaking it for chlorine.
The solution is to not let your chlorine level get to low and anticipate a raise in organic material level.
Stinging eyes can also be caused by the acidity level of your pool being to high, so always check this possibility too.
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- I've got a lot of people coming to swim later, should I do anything now?
It is always a good idea to anticipate the usage your pool is going to get and plan for it.
With light use a level of 1.5 ppm of chlorine is fine and can be easily maintained using Trichlor Tablets. But if lots of bodies jump in your
pool bringing with them whole skinfulls of bacteria and lose skin cells your chlorine could be overwhelmed. If you know they are coming a few hours before add
some more Chlorine Granules to the water, enough to raise the chlorine level to about 4-5 ppm. That way the bugs will get killed straight away and your chlorine will
be used up but not fall too low.
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- Should I use granular chlorine or Trichlor tablets?
Both, probably. Granules and tablets do the same thing but in different ways.
Tablets maintain the chlorine level all the while you have the filter running and are easy to use and maintain. With granules the actual level of
chlorine is easy to control. So long as you know the volume of your pool you can work out how much granules to add to raise the chlorine level to where you want
it. Tablets maintain your underlying chlorine levels and granules adjust the level depending on the circumstances (e.g. heavy usage, very sunny weather)
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- I'm sure there is chlorine in my pool (or spa) but it reads zero when I test it?
You have probably got so much chlorine in there that you have bleached out the reagent that does the testing.
What you need to do is 'dilute' your sample and test again. Take a measure of pool water and add it to an equal measure of tap water. Then test this mixture. If you get a reading then you must double it to get the true reading. If you still don't get a reading then put in two measures of tap water to one of pool water and multiply by three and so on until you do get a reading.
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