| FACTS AND FORMULAS |
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Volume calculations
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Length x width x average depth x 7.5 = volume (in gallons) of square or
rectangular pool |
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3.14 (pi) x radius squared x average depth x 7.5 = volume (in gallons)
of a round pool |
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0.45 x (A+B) x length x average depth x 7.5 = volume (in gallons) of
kidney or irregular-shaped pool |
Negative Edge Basin Sizing
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Basin Width= square root of (.25 X Area of the pool / Length of the weir
wall) |
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Basin Depth= Basin Width + 1.75’ |
Measurements
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7.5 gallons in each cubic foot of water |
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1 inch = 0.0833 feet |
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Radius = diameter divided by 2 |
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1 gallon of water weighs 8.3 pounds |
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1 gallon of chlorine weighs 10 pounds |
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16 ounces dry weight = 1 pound dry weight |
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128 ounces liquid = 1 gallon |
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8 ounces liquid = 1 cup liquid |
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1,000 watts = 1 kilowatt |
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1 milliamp = 0.001 amp (30 milliamps will cause muscle contractions) |
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1 psi = 2.31 feet of head (resistance) |
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1 psi - 28 inches water column pressure (WCP) |
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1 inch of mercury = 1.13 feet of head |
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1 micron = one-millionth of 1 meter = 0.0000394 inches (the human eye
can detect objects a small as 35 microns) |
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1 grain of table salt = 100 microns |
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3/4 volt of 1 volt = 750 millivolts = 0.75 volts |
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1 BTU (British Thermal Unit) is the amount of heat required to raise 1
pound of water 1°F |
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1 therm (measurement of gas supply) = 100,000 BTU per hour |
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1 gallon of fuel oil = 140,000 BTU |
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1 kilowatt = 3412 BTU |
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1 gallon of fuel oil = 140,000 BTU |
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1 ton (heat pump rating) = 15,000 BTU |
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A typical bather displaces 2 cubit feet of water |
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1 gallon of fuel oil = 140,000 BTU |
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1 hp = 746 watts |
Chlorine Comparison Chart
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| Product Form |
PH Stability |
Available Chlorine |
Common |
| C12 gas |
Low |
100% |
Gas |
very unstable |
| Sodium hypochlorite |
13+ |
12.5% |
Liquid |
unstable |
| Calcium hypochlorite |
11.5 |
65% |
Dry granular |
stable |
| Dichlor |
6.8 |
60% |
Dry granular |
very stable |
| Trichlor |
3.0 |
90% |
Tablet (or granular) |
very very stable |
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Effectiveness Comparison
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1 pound C12 gas = 1 gallon sodium hypochlorite = 1.5 pounds
calcium |
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Hypochlorite = 1.75 pounds dichlor = 1.15 pounds trichlor = 2.8 pounds
lithium hypochlorite |
Cost Comparison
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Sodium hypochlorite = 2 times the cost of chlorine gas |
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Sodium hypochlorite = 2 times the cost of chlorine gas |
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Calcium hypochlorite = 3 times the cost of chlorine gas |
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Dichlor = 5 times the cost of chlorine gas |
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Trichlor = 3 times the cost of chlorine gas |
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Lithium = 5 times the cost of chlorine gas |
95% of chlorine in water can be lost on a sunny day in
two hours (without stabilizer).
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Amount of product required to
obtain a change in 1000 Gallons of Water
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| Item |
Raise or Lower 10 ppm |
Product |
| Product Amount Required (dry weight
unless otherwise noted) |
| Calcium hardness |
Raise |
Calcium Chloride |
2 ounces |
| Total Alkalinity |
Raise |
Bicarb of Soda |
2.5 ounces |
| Total Alkalinity |
Lower |
Sodium Bisulfate (dry acid) |
2.5 ounces |
| Total Alkalinity |
Lower |
Muriatic Acid |
1/4 Cup (Liquid) |
| Stabilizer |
Raise |
Cyanuric Acid |
1.5 ounces |
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Amount of chlorine needed to raise
residual in 1000 Gallons of water by 1 ppm (multiply results by 30 for super
chlorination procedures).
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| Availability of Product (Percent) |
Product Amount |
| 12 |
1/8 Cup (Liquid) |
| 50 |
1/4 Ounce (dry weight) |
| 80 |
1/6 Ounce (dry weight) |
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Standards
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Water may not move at more than 8’ per second through copper pipe. |
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Water may not move at more than 7’ per second through PVC (Some pipe
manufacturers will not warranty over 5’ per second do to concerns over water
hammer.) |
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Water may not move at more than 6’ per second through any type of
suction pipe. |
Conversion Table
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| Gallons to Liters |
Gallons x 3.785 = Liters |
| Liters to Gallons |
Liters x 0.2642 = Gallons |
| Ounces to Milliliters |
Ounces x 29.57 = Milliliters |
| Milliliters to Ounces |
Milliliter x 0.0338 = Ounces |
| Inches to Millimeters |
Inches x 25.4 = Millimeters |
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Data
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Normal rotation speed of a pump motor is 3450 rpm (revolutions per
minute). On two-speed pumps, the low speed rotates at 1750 rpm. |
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Alternating current (ac) in the United States runs on 60 hertz (cycles).
In Europe and many other foreign countries, it runs at 50 hertz. |
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PVC plumbing is designed to carry water at temperature of less than
100°F |
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CPVC plumbing is designed to carry water at temperatures above 100°F. |
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Head created by various plumbing and equipment components: |
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A 1-1/2” x 90° elbow = 7.5 feet of straight 1-1/2” pipe |
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A 2” x 90° elbow = 8.6 feet of straight 2” pipe |
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A 1-1/2” x 45°elbow = 2.2 feet of straight 1-1/2” pipe |
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A 2” x 45° elbow = 2.8 feet of straight 2” pipe |
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Filters create 5 to 7 feet of head |
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Heaters create 8 to 15 feet of head |
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Sand filters strain particles as small as 60 microns |
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Cartridge filters strain particles as small as 20 microns |
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DE filters strain particles as small as 7 microns |
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A 1 pound coffee can holds 1/2 pound of DE |
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1 pound of DE will coat 10 square feet of filter grid area. |
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Sand filters are designed to use #20 silica sand |
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Electricity supplied to an electronic ignition pilot is 10,000 to 20,000
volts |
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The chemical processes when chlorine (in any form) is added to water
C12 (chlorine) + H2O (water = HC1 (muriatic acid) +HOCI
(hypochlorous acid)
HOC1 = H+ + OC1-2 (a positive ion of hydrogen and a negative ion of
hypochlorite)
At pH 7.2 = 80% killing HOC1 +20% useless OC1
At pH 8.0 = 20% killing HOC1 + 80% useless OC1 |
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Urine and perspiration = ammonia |
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One active swimmer produces approximately 1 quart of ammonia per hour |
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Liquid chlorine is sold in a solution of 10 to 15 percent strength |
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Pools must turn over in 6 hours |
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Spas must turn over in 1/2 hour |
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Wading pools must turn over in 1 hour |
Filtration Standards
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| Filter Style |
Maximum Flow (gpm/sq. ft.)
Minimum Backwash Flow
(gpm/sq.ft.) |
| High-rate sand |
15 |
15 |
| DE |
2 |
2 |
| Cartridge |
0.375* |
No Backwash |
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*Note that cartridge filters are rated at 1 gpm/square
foot maximum flow rate on most residential applications and the more
stringent 0.375 gpm/square foot on commercial installations
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Rapid sand filters are designed for flow rates of less than 3 gpm |
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High-rate sand filters are designed for flow rates of 5 to 20 gpm |
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High-rate sand filters are designed for flow rates of 5 to 20 gpm |
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The normal filter operating pressure differential (between incoming pipe
and outgoing) is between 2 and 4 psi. When it reaches 10 psi, the filter
must be cleaned. Expressed another way, if you know the normal operating
pressure of your filter (as observed on the pressure gauge), you must clean
the filter when the pressure is more than 10 psi higher. |
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Water flow must not exceed 100 gpm through 1-1/2” heater plumbing |
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Water flow must not exceed 125 gpm through 2” heater plumbing |
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Water flowing out of a heater should not be more than 10°F warmer than
the water flowing into the heater |
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Pool water should not exceed 82°F |
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Spa water should not exceed 104°F |
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The on/off switch of a millivolt heater must not be located more than
20’ from the heater |
Heater Installations
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The rear and non-plumbed sides must have a least 6” of clearance |
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The plumbed side must have a least 18” of clearance |
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The front must have at least 24” of clearance |
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The top must be at least 5 feet below (and 4 feet horizontal
distance) any window, door or vent |
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PVC gas lines must be buried at least 18” below ground (12 inches below
concrete) |
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Metal gas lines must be buried at least 12” below ground (6 inches below
concrete) |
Recreational Water Chemistry
Parameters
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| Chlorine Residual |
1.0 to 3.0 ppm |
| Total Alkalinity |
80 to 150 ppm |
| pH |
7.4 to 7.6 |
| Hardness |
200 to 400 ppm |
| Total Dissolved Solids |
Less than 2000 ppm |
| Cyanuric Acid |
30 to 80 ppm |
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FORMULAS
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75% of the surface area of a pool is the required surface area of solar
panels to adequately heat the pool |
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Each spa jet requires flow of 15 gpm |
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Each spa jet requires 1/4 hp from the pump and motor |
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To estimate the horsepower of a blower: |
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1 hp = 6.5 amps at 110 volts = 3.25 amps at 220 volts |
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2 hp = 13 amps at 110 volts = 6.5 amps at 220 volts |
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Volts x amps = watts |
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Heater BTU output rating divided by (gallons x 8.33) = degrees
temperature rise/hour |
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Breakpoint chlorination method (for every 20,000 gallons of water): |
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1 gallon of anhydrous ammonia + 8 gallons liquid chlorine |
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Leak water loss conversion inches to gallons |
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Water loss in inches x (Surface Area divided by 100) x 62.5 = loss |
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