The Bromine
Schedule
How to
convert and sanitise your swimming pool with bromine.
These are quick instructions. For further
details, click on the links or see the
glossary below.
PLEASE
NOTE - All
dosages given are for 50,000 litre pools. For other sizes simply pro rata
the dosage. The objective to to establish and maintain a
bromine bank of
at least 25 ppm.
Anything up to 1,000 ppm is acceptable with cost being the only
consideration.
Less than 25 ppm - it simply will not work. So better the err on on
high side.
VERY
IMPORTANT: Some types of pH test (Phenol Red)
do not work properly with bromide
and serious errors could occur if this is not correctly understood.
STARTING OUT
- with new water or converting an existing pool to Bromine the
Bromine Bank has to be
establish. It is always best to do this early in the year, when the water is
cool and not a lot of bathing going on. For some reason, that I have not
been able to establish, there is always a high oxidant (chlorine or
monopersulphate) demand
when the bromine bank is first
established or increased.
The process is as follows -
1. Check the
total alkalinity and balance
the water.
2. Hoover and backwash thoroughly.
3. Add 1.5 Kgs Bromine Salt (Sodium Bromide) into the skimmer, with the
filter running on "Circulation" and wait 10 minutes for it to disperse
throughout the pool.
4. Shock to 12 ppm. Best with liquid chlorine (Sodium Hypochlorite).
5. The following day: Test for Total Bromine with a DPD test kit. If this is less than 4 (2 on
the Chlorine scale) then shock again and continue shocking until you get a
result.
6. Maintain the pool in the normal way buy adding oxidants (chlorine product
or monopersulphate) to achieve the required sanitizer level, pH and total
alkalinity but monitor the pool every 2/3 days until it has settled down.
If the sanitizer should disappear then shock again. Don't waste money on
trichlor or monopersulphate, liquid chlorine is much cheaper.
Thereafter you
only need to maintain the bromine bank annually and add sufficient sodium bromine to
make up for water loss. This is a lot less than you would think because
evaporation does not count as water loss - only backwashing and splashing
out. As long as the pool does not leak then this is only 20% to 25%.
There is now a test for bromine bank.
However, best not to worry, you either have a leak (in which case it is best
to start over every spring), or you don't have a leak and it is safe to
assume 25% water loss.
EARLY SPRING (March/April) - Maintain the
Bromine Bank exactly as above
but just add 0.35 Kgs Sodium Bromide.
REGULAR VISITS THROUGHOUT THE YEAR
The
frequency of these visits obviously varies but should not be less than
every 20 days from November to April and at least every week during the Summer or
whilst the pool is in use.
1. Adjust the Free Bromine Level.
2.
Check and adjust the pH to 7.6 to 8.0. If large variances are noticed
then check and adjust the
total alkalinity.
3. Observe the
water quality and shock if necessary. Shocking is only likely to be
necessary if there has been exceptional bather lead, bather abuse or a
fault with the purification plant.
This at
is really all you need to do! More details of the different tasks are
provided in the glossary below.
Bromine Bank: The amount of Bromine Ion
that is available in the water. This is introduced by adding Bromine Salt
(Sodium Bromide) to the water to provide at least 25 ppm. There is no
upper limit.
Bromine Chemistry: When chlorine is added to water in any form
(gas, liquid or solid) Hypochlorous Acid is formed - this is the chlorine
sanitizer. If sufficient Bromine Ion is present then Hypobromous Acid is
formed - this is the bromine sanitizer. The chlorine disappears from the
water after oxidising the bromine.
Bromine can also be oxidised with monopersulphate.
When the bromine sanitizer has done its work the Bromine Ion returns to the
water for re-use.
Bromamines: Bromine sanitizer
reacts with bather waste to form bromamines. These are as good a sanitizer
as the bromine itself. They have hardly any odour and have no harmful effect
on eyes or skin.
Chloromines: Chlorine sanitizer
reacts with bather waste to form cloramines, which are undesirable in pool
water because they cause stinging eyes and skin and an unpleasant chlorine
odour.
Chloramines should be removed by
shocking as soon as more than 0.05 ppm have formed.
Phenol Red: A chemical used to test the pH
of pool water. The colour changes from strong yellow (pH 6.8 - Acidic),
through shades of orange to strong pink (pH 8.2 Basic). The actual pH is
read off against a colour comparator supplied with the test kit.
Phenol red is affected by bromine sanitizer and shows a purple/brown
colour, making the test colour completely completely false. The
real danger however is that, if the tester is unaware of this, the test
could be interpreted as very high pH when it is in fact very low.
Thereafter the addition of pH-minus chemicals could have disastrous
consequences.
There are various solutions: Some test kits are specially prepared for
this or 2 drops of sodium
thiosulfate can be added to the test water prior to the addition of the
phenol red.
Whenever a pH anomaly is noticed, the best practice is always to do
Total
Alkalinity test before adding chemical to adjust the pH.
Total
Alkalinity and Water Balancing - Correct water balancing is a
"trade off" between Calcium Hardness, Total Alkalinity and pH. A perfect,
but rather complicated, test of properly balanced water is provided by using
the Langlier Index but there is little need to resort to this unless a
serious anomaly is noticed.
The whole objective is to achieve a water balance that is neither acidic
(corrosive) not heavily scale-forming and with a stable pH within the
recommended range which, in the case of Bromine can be between 7.6 and 8.0.
Costa Blanca water generally has Calcium Hardness within the correct
range. This can be ignored as long as there is no serious anomaly. However
it should be noted that there would be a real problem if the pool is filled
via a water softener as these remove all dissolved calcium and it has to be
put back.
Which leaves us with just total alkalinity and pH with the
latter being the dominating factor.
Certain facts should be taken into account whilst trying to determine the
suitable pH -
a) Costa Blanca water generally has a high TA (around 180).
b) TriChlor (tablets and granules) are acids and cause the TA to reduce.
Consequently, during warm weather and heavy use the TA will fall. Over a
whole year there would probably be a gradually drift downwards.
c) The recommended TA is between 80 and 120. However cyanuric acid distorts
the test and 30% of the CYA has to be deducted from the actual test reading.
With high CYA (say) 300 ppm a proper TA balance becomes impossible because
this would mean 170 to 210, which could result in a pH of well over 8.2.
Therefore we have the trade-off between TA and pH and the optimum TA is the
level at which the pH is stable within the correct range.
Adjusting the
pH/TA - is just a question of understanding the different pH-plus and
pH-minus chemicals.
I recommend using the Taylor test kit because this comes with charts for
product amounts for different size pools.
To lower the
pH with little affect on the TA: Trickle Sulfumant (Muratic Acid) very
slowly in the return-jet stream so that the product is slowly dissipated
throughout the pool.
To lower the pH and the TA: Pour the Sulfumant slowly into a single
column in the deep end with the pump off and wait 30 minutes before starting
it up.
To raise the pH with little affect to the TA: Use Soda Ash (Sodium
Carbonate).
To raise the pH and the TA: Use Baking Soda (Sodium Carbonate).
For general,
practical purposes you should never need Carbonate in Costa Blanca and slight adjustments to
the pH with Bicarbonate will usually take care of the TA as well over long
periods.
High pH with
low TA, usually also turbid (or even green) water. A real head-banger to
deal with? Not really, you probably just have a lot of alkaline debris,
which can easily happen if there has been bather abuse or neglect.
The low TA is the real indicator. Get the bathers out of the water and do a
heavy shock before anything, you would probably find that the pH falls
dramatically and then you'll know exactly what to do.
Cyanuric Acid:
When TriChlor is dissolved in water Hypochlorous Acid and Cyanuric Acid
(CNOH)3 are produced. The Cyanuric Acid (CYA) acts as a stabiliser and,
without the CYA, the chlorine would disappear quickly from the water,
especially in strong sunlight - but a real problem can occur if there is too
much!
What happens is that “normal” chlorine levels cease to work properly, more
and more TriChlor is required (adding more and more CYA) until there is so
much that the chlorine "locks-up" completely.
The correct way to use TriChlor means regular shocking with liquid chlorine
or monopersulphate (neither contain CYA) and by draining part of the water
each year to keep the level between 30 and 100 ppm.
The real problem here is that water is expensive as well as the extra visits
required by a professional pool technician. Bromine is not affected by
CYA.
Wikipedia: Swimming Pool Sanitation
Ask Alan Schuster: Chlorine Pools
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