LaMotte Pool & Spa Owner's Handbook - Manual (Page 35)

ADJUSTING HARDNESS
It is recommended that dry chemicals first be mixed into a generous
amount of pool water in increments of about two pounds (1 kg), and the
predissolved mixture be distributed evenly around the pool unless
directed otherwise.
Precautions
n
Never add water to chemicals; always add chemicals to water.
n Never add calcium chloride to skimmer since it produces heat upon
mixing with water.
n
Always follow manufacturer’s recommendations and warnings
on product labeling.
n Never mix two chemicals together since their pH might vary
and could cause an explosion or fire.
In most areas of the country a minimum of 150 ppm and an ideal range
of 200-400 ppm of hardness is recommended. The only practical way
to lower hardness is to drain some water from the pool or spa and refill
with water that is lower in hardness.
Once you determine the hardness concentration, calculate how much
you wish to add and find this number in the left-hand column. Match this
with the volume of water in the pool or spa, listed at the top of the table.
Be careful when mixing calcium chloride with water since this can
generate a significant amount of heat. Allow the water to circulate
4-8 hours after the chemical is added and then check the hardness.
33