Swimming Pool Chemicals Part Three-Shock

y">All three shocks are available in convenient 1 lb.
Anytime a pool is getting heavy use chlorine levelspouches or in pails up to 50 lbs. Cal hypo is the
will drop as free chlorine combines withcheapest and most popular, lithium the most
contaminants and forms chloramines. Chloraminesexpensive and least used. Dichlor is mid priced and
cause that heavy "chlorine" smell any swimmerwidely available. All three types require the pool to
knows and loves. Though attributed to too muchbe closed until chlorine levels drop below 3 ppm.
chlorine it's actually the best indicator that chlorineNon Chlorine shock
is way too low! The pool needs a big dose ofA relatively new development, non-chlorine shock
chlorine right away or bad things will happen. Thishas proved to be a popular choice with many pool
is where pool shock comes to the rescue.owners primarily because the pool can stay open
Designed to add lots of chlorine in just minutesfor use even after shock is added. Pretty cool,
shock products are often the same stuff you usehuh?
day to day but in a different form. There areSort of. Non-chlorine shock, as one might expect,
two kinds of shocks; chlorine based andcontains no chlorine. If chlorine is what a pool
non-chlorine. Each is useful but in differentneeds how does this stuff do any good? The
situations.active ingredient in non-chlorine shock is potassium
Chlorine shockmonopersulfate or PMP. It has little if any oxidizing
Chlorine shock comes in three forms; calciumpotential but it does do something pretty neat.
hypchlorite (Cal Hypo), sodium dichlor ()Dichlor) orPMP actually frees chlorine bound up in chloramine
lithium hypochlorite(Lithium). Cal hypo and dichlorcompounds and makes it available to sanitize
were discussed in Part One of this series asagain. And the pool can stay open while this
regular sanitizers. Lithium hypochlorite is only usedmiraculous process takes place. There is a catch.
as a shocking agent. In each of these productsOften after prolonged summer use pool water
the chlorine molecule is carried or bound to ahas little or no chlorine or chloramines. Sunlight and
different substance; lithium, sodium or calcium.bather load has used up almost everything. Adding
Lithium and sodium dissolve nicely in pool water,non-chlorine shock at this point will do nothing
calcium doesn't so lithium and dichlor can be addedbecause the PMP has nothing to work with. Make
directly to a pool while calcium should be dissolvedsure to take a total chlorine reading before using
in a bucket of water before adding. If notnon-chlorine shock. If total chlorine is low use a
pre-dissolved Cal Hypo will settle to the bottomshock containing chlorine.
and bleach lots of nice little white spots on a vinylUsing Shock Properly
liner.-Regardless of the type used it's best to add
A shocking agent is meant to be a quick fix. Theshock when people are done using the pool for
chlorine level is raised to a level as high as 10 ppmthe day. The overnight hours are best because
(parts per million), too high for swimming. Sinceunstabilized chlorine will last longer. Remember to
unstabilized chlorine is quickly burned out byrun that filter.
sunlight, cal hypo and lithium are nice shock agents-Always try to verify that shocking your pool has
as they are both unstabilized. Dichlor, however, ispushed chlorine levels to at least 5 ppm. Lower
stabilized and will hang around for up to six hours.concentrations won't do a proper job and could
Dichlor is fine but don't plan on using the pool for alead to trouble.
while.-It's good practice to pre-dissolve shock before
Dichlor and Cal Hypo both pack a powerful punchadding to the pool even if it's lithium or dichlor.
with 56 and 65 percent available chlorineAlways add shock to water NOT water to shock.
respectively. Lithium usually provides 35 percent-Remember, non-chlorine shock WILL NOT WORK
and is a relatively weak sister requiring a heavierif chlorine levels are too low.
dose for the same results.