Pool Controls SWC Series User Manual page 8

Minerals and pH: the magnesium in mineral salts can form a soft scale on the cell even
though it is reversing polarity. This is minimised by keeping the pH at the lower range for
your pool type. The use of hydrochloric acid is recommended for magnesium mineral
systems.
Total Alkalinity (TA)
Total alkalinity is also known as carbonate hardness or TA for short. The recommended
level is between 80 and 120ppm. TA is related to pH in that it stops the pH from varying
quickly with small additions of acidic or alkaline chemicals. When the TA is low it is almost
impossible to control the pH. To raise the TA, buffer (sodium bicarbonate) is added. This
must be done slowly as buffer will also cause the pH to rise. As an approximate rule every
increase of 20ppm of TA will also cause a 0.1 rise in pH. Once buffer is added it should be
left to mix in the pool for a few hours before reducing the pH.
Phosphates and Nitrates
Phosphate and ammonia nitrogen will make your garden green – and they will do the same
thing to your pool. Check for phosphates and add phosphate remover if necessary. Don't
let fertiliser get into your pool! Phosphates are also in some cleaning products – check the
label if using around your pool.
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