Frequently Asked Questions

Change from packaged Chlorine to Salt chlorine generation

Some day we will have a better way of determining what size salt generator a given pool should have. For now, the best way to determine the size is to find out how much chlorine you are using now and then divide that by the percentage of available chlorine in the product.

For instance if you used say 50 pounds of trichlor in a month then you average daily usage would be 1.66 pounds per day. Then divide this by .90 (because trichlor provides 90 % available chlorine) and you get 1.86 pounds. Therefore you need a unit that is capable of supplying a minimum of 1.86 pounds per day. And if you only run your pool for 12 hours per day then you need to double that.

Another consideration is that you will lose about 1.0 to 1.5 ppm of free available chlorine (FAC) per day due to sunlight (UV) degradation even with cyanuric acid (CYA) in the water at 50 ppm. Each 1 ppm of FAC in 10,000 gallons of water is 1.3 oz. of pure chlorine.For a 40,000-gallon pool that would be 4 X 1.3 or about 5.2 oz. of pure Chlorine - about 1/3 of a pound. So you will at least need a a unit that will make 1/3 pound a day. If you are running your pool 12 hours it will need to make that 1/3 pound in 12 hours. This is only for sunlight and background chlorine demand. Bathers will use about .5 ppm FAC per day each.

A final consideration for commercial pools and sizing is that you want a device that is capable of providing a minimum of 1.0 ppm of FAC in the pool it is installed on in one hour. (Remember I said commercial.) And some health departments are considering a unit capable of supplying 2 ppm in 1 hour. This would also be true for a chlorinator, not just a chlorine generator. This recovery time and ppm is becoming more and more important.

The logic is this. If you had a large enough bather load and they used up all of the FAC in the pool, how soon would your sanitation system be able to put it back? Hours from now is not acceptable.

Why is my pool cloudy ?

Cloudy water is a nuisance, it looks uninviting and it can create a safety hazard. There are five causes why pool water gets cloudy. Cloudy water results from one or more of the following:

1. improper water balance
2. low sanitizer or oxidizer level
3. poor or inadequate circulation/filtration
4. extremely high bather load
5. chemical incompatibility

These five causes will cover probably 99 percent of all cloudy water problems you are likely to encounter on a daily basis. There are a few other causes such as a car being driven into the pool, a flock of geese lands in the pool or some deliberate act. But even those might be covered under our broad causes above.

If you correct, check or perform these five causes, you will have crystal clear water - I guarantee it!

1. Balance the water. Adjust all chemical operation parameters to the proper range. High levels of calcium and magnesium hardness, high total alkalinity and high pH can all cause cloudy water. Bringing these readings into the NSPI-recommended ranges may clear up the water. And it’s the easiest one of the five to do because these things need to be corrected regularly and the chemicals needed should already be near the pool.

NSPI Recommended Ranges:
Min. Ideal Max.
pH 7.2 7.4-7.6 7.8
Total Alkalinity 60 ppm 80-140 ppm 160 ppm
Calcium Hardness 150 ppm 200-400 ppm 500-1000 ppm

2. Check for proper sanitizer or oxidizer levels. Bacteria and algae can cause the water to look cloudy. Superchlorination or shock treating with a non-chlorine treatment chemical may be required. The chlorine or bromine in the water can combine with contaminants brought in by a rain storm, dust storm or a heavy use period and become less effective. The water can turn hazy, cloudy or dull.

Superchlorinate by adding “enough” chlorine to bring the FAC (free available chlorine) up to 10 ppm or higher and keep it there for at least four hours - the longer the better. All chlorine products that can be used for superchlorination have label directions for using specific types of chlorine products. Follow label directions.
Shock treat the water by adding one of the following non-chlorine shocking chemicals: potassium peroxymonosulfate, sodium persulfate, hydrogen peroxide or sodium percarbonate. Follow label directions.

Again, superchlorinating and shock treating chemicals should already be on hand making this the next easiest step.

3. Check your circulation/filtration system. If the filter is not properly sized to the pool or the circulation/filtration system is not operating a sufficient number of hours per day, cloudy water can result. Most circulation/filtration systems must operate a minimum of six hours every day. Check the filter grids in the D.E. (diatomaceous earth) filter. Make sure they are clean, in good condition, not frayed or torn.

On cartridge filters, make sure the cartridges are clean and in good condition, not ripped or torn. Check to see if the cartridges are seated properly and make sure the “O” rings are in place and not cracked. Use a recommended “O” ring lubricant.

Is the sand in a hi-rate sand filter getting old? Most manufacturers suggest replacing the sand every three to five years. Is the sand clean? Has the system been backwashed? Does the filter have enough sand?

Many manufacturers have products for cleaning filters. They have been tested and usually work better than home remedies or household cleaners. However, if you do decide to do it yourself, use a good detergent first, then use an acid. Using acid first can sometimes react with chemicals on the filter and seal them in place.

The circulation/filtration system should run 24 hours a day when you have a cloudy water problem.

If everything described above appears normal, it’s possible that the particles that are making the water look cloudy are too small to be trapped by the filter. In this case, you will need some chemical assistance. There are any number of organic and natural polymers on the market for clarifying water. These products all coagulate and agglomerate small particles so they can be trapped by the filter or fall to the bottom where they can be vacuumed up. Many companies still sell and use alum for this purpose as well.

4. High bather loads. Sometimes the problem is just too much stuff brought in by bathers or swimmers. This is usually suntan oils and lotions, soap, makeup and other personal care products. The best way to stop this from clouding the water is to have bathers and swimmers shower or rinse off before entering the water. If you can not police this and get people to do it, you may have to deal with the problem. Most clarifiers are not real good at removing bather- introduced stuff. However, enzymes can be a great help in these situations. Enzymes work slowly, but they do reduce the soap, oil and grease to carbon dioxide and water.

5. Chemical incompatibility. Sometimes the problem is a chemical incompatibility. This usually happens when a chemical is added to solve a problem and it doesn’t work. Then, another chemical is added to solve the same problem. It also happens when chemicals are added too close to one another. Here are some examples.

If you add a scale inhibitor chemical to the water and the same day add a clarifier, you will cloud the water. If you add a scale inhibitor and chlorine on the same day, you cloud the water. If you add soda ash and hardness increaser you cause clouding. Customers often claim that they have not done this and it takes being something of a detective to find it out.

The water may never clear up if two incompatible chemicals are in it. The best thing to do is to drain the water and start over. If a complete draining is out of the question, (vinyl liner pools should never be drained more than half) at least drain 1/4 of the water and refill.

If you have gone through all the above steps and still have cloudy water you should drain 1/2 or all of the water.

There is one other condition in the water that may cause clouding. Copper in the water with biguanide biocides such as Baquacil® and SoftSwim® can cause cloudiness. In these cases, you need to use a biguanide compatible metal sequestering agent.

If you follow all of the above, you will have clean, clear, sparkling water, I guarantee it.

How much salt ?

To start up a salt generator the usual level of salt in the water is 2500 to 3000 ppm. In a 10,000 gallon pool that would be about 200 to 250 lbs of salt. A 25,000 gallon pool would need more than 500 lbs. Always test the water for salt before adding more salt.

The type of salt to use is granulated, evaporated, non-iodized salt. Be careful, many salt products contain tricalcium phosphate to prevent caking. It's insoluble and ends up on the bottom or in the filter. Watch out for iodine. Do not use rock salt or water conditioner salt.

The salt makes chlorine (technically HOCl, the killing form of chlorine and OCl-, the fairly inactive form) and sodium hydroxide and hydrogen gas. When the chlorine is used in oxidation, it becomes chloride. The chloride is recycled back to chlorine. In a perfect world, you would only have to add chloride (salt) once. However, some reactions of chlorine with organic material tie up or use up the chlorine making it unavailable to be recycled. Therefore, the water must be tested periodically to make sure the salt content is OK.

Most units are capable of making about a pound of pure chlorine per day (if run 24 hours). One pound of chlorine in 10,000 gallons of water would be 12 ppm.

 

The chloride (Cl) portion of NaCl is .606731. Therefore, the 5,000 ppm NaCl is 3,033.655 ppm Cl and 1,966.345. Na.

Pool Size in gallons (US)

 

Salt Amount Before Addition



10,000



12,000



14,000



16,000



18,000



20,000



22,000



24,000



26,000



28,000



30,000

0.00 gpl

250 lbs

300 lbs

350 lbs

400 lbs

450 lbs

500 lbs

550 lbs

600 lbs

650 lbs

700 lbs

750 lbs

0.20 gpl

230 lbs

280 lbs

325 lbs

370 lbs

420 lbs

465 lbs

510 lbs

560 lbs

605 lbs

650 lbs

700 lbs

0.40 gpl

215 lbs

260 lbs

305 lbs

345 lbs

390 lbs

435 lbs

475 lbs

520 lbs

565 lbs

605 lbs

650 lbs

0.60 gpl

200 lbs

240 lbs

280 lbs

320 lbs

360 lbs

400 lbs

440 lbs

480 lbs

520 lbs

560 lbs

600 lbs

0.80 gpl

185 lbs

220 lbs

255 lbs

290 lbs

330 lbs

365 lbs

400 lbs

440 lbs

475 lbs

510 lbs

550 lbs

1.00 gpl

165 lbs

200 lbs

230 lbs

265 lbs

300 lbs

330 lbs

365 lbs

400 lbs

430 lbs

465 lbs

500 lbs

1.20 gpl

150 lbs

180 lbs

210 lbs

240 lbs

270 lbs

300 lbs

330 lbs

360 lbs

390 lbs

420 lbs

450 lbs

1.40 gpl

130 lbs

160 lbs

185 lbs

210 lbs

240 lbs

265 lbs

290 lbs

320 lbs

345 lbs

370 lbs

400 lbs

1.60 gpl

115 lbs

140 lbs

165 lbs

185 lbs

210 lbs

235 lbs

255 lbs

280 lbs

305 lbs

325 lbs

350 lbs

1.80 gpl

100 lbs

120 lbs

140 lbs

160 lbs

180 lbs

200 lbs

220 lbs

240 lbs

260 lbs

280 lbs

300 lbs

2.00 gpl

85 lbs

100 lbs

115 lbs

135 lbs

150 lbs

165 lbs

185 lbs

200 lbs

215 lbs

235 lbs

250 lbs

2.20 gpl

65 lbs

80 lbs

95 lbs

105 lbs

120 lbs

135 lbs

145 lbs

160 lbs

175 lbs

185 lbs

200 lbs

2.40 gpl

50 lbs

60 lbs

70 lbs

80 lbs

90 lbs

100 lbs

110 lbs

120 lbs

130 lbs

140 lbs

150 lbs

2.60 gpl

30 lbs

40 lbs

45 lbs

55 lbs

60 lbs

65 lbs

75 lbs

80 lbs

85 lbs

95 lbs

100 lbs

2.80 gpl

15 lbs

20 lbs

20 lbs

25 lbs

30 lbs

30 lbs

35 lbs

40 lbs

40 lbs

45 lbs

50 lbs

 

Pounds of Chlorine Stabilizer (Cyanuric Acid) Needed to Obtain 75 PPM

 

Pool Size in gallons (US)

 

Stabilizer Level Before Addition



10,000



12,000



14,000



16,000



18,000



20,000

00 PPM

6.25 lbs.

7.50 lbs.

8.75 lbs.

10.0 lbs.

11.25 lbs.

12.5 lbs.

10 PPM

5.40 lbs.

6.50 lbs.

7.60 lbs.

8.60 lbs.

9.75 lbs.

10.8 lbs.

20 PPM

4.60 lbs.

5.50 lbs.

6.40 lbs.

7.30 lbs.

8.25 lbs.

9.20 lbs.

30 PPM

3.75 lbs.

4.50 lbs.

5.25 lbs.

6.00 lbs.

6.75 lbs.

7.50 lbs.

40 PPM

2.90 lbs.

3.50 lbs.

4.00 lbs.

4.60 lbs.

5.25 lbs.

5.80 lbs.

50 PPM

2.00 lbs.

2.50 lbs.

2.90 lbs.

3.30 lbs.

3.75 lbs.

4.10 lbs.

60 PPM

1.25 lbs.

1.50 lbs.

1.75 lbs.

2.00 lbs.

2.25 lbs.

2.50 lbs.

70 PPM

0.40 lbs.

0.50 lbs.

0.60 lbs.

0.66 lbs.

0.75 lbs.

0.80 lbs.

75 PPM

None

None

None

None

None

None

 

Stabilizer Level Before Addition



22,000



24,000



26,000



28,000



30,000

00 PPM

13.75 lbs.

15.0 lbs.

16.25 lbs.

17.5 lbs.

18.75 lbs.

10 PPM

11.9 lbs.

12.9 lbs.

14.0 lbs.

15.2 lbs.

16.25 lbs.

20 PPM

10.0 lbs.

10.9 lbs.

11.9 lbs.

12.8 lbs.

13.75 lbs.

30 PPM

8.25 lbs.

9.00 lbs.

9.75 lbs.

10.5 lbs.

11.75 lbs.

40 PPM

6.40 lbs.

6.90 lbs.

7.58 lbs.

8.20 lbs.

8.75 lbs.

50 PPM

4.60 lbs.

4.90 lbs.

5.40 lbs.

5.80 lbs.

6.25 lbs.

60 PPM

2.75 lbs.

3.00 lbs.

3.25 lbs.

3.50 lbs.

3.75 lbs.

70 PPM

0.90 lbs.

1.00 lbs.

1.10 lbs.

1.20 lbs.

1.25 lbs.

75 PPM

None

None

None

None

None

 

Tip:
Add 1 1/4 lbs. Of Chlorine Stabilizer every time you need to add 50 lbs. of salt to the pool. The Chlorine Stabilizer reading should be maintained at 75 PPM

How rain affects your pool

Rain brings all of the airborne pollution that is in the atmosphere right into the pool. All the pollen, mold spores, seeds, all the stuff that comes from living things like trees, grass, weeds, flowers, etc. In addition to the nature stuff is man-made pollution - stuff like nitrogen compounds, sulfur compounds, ozone, CO2, CO, hydrocarbons, etc. The nitrogen and sulfur compounds (mostly nitrous oxide and sulfur dioxide - NOx and SO2) are fertilizer for any existing algae and food for any new pollen or spores brought in by the rain. In addition to being food, NOx and SO2 use up big amounts of chlorine. They eventually become nitrites and nitrates and sulfates in the water. CO and CO2 are used by plants during photosynthesis. Hydrocarbons are tough to destroy and chlorine wears itself out trying to oxidize them.

You will always have an algae bloom or new algae growing after a rain. It is best to superchlorinate as soon as you can after a rain. 

How shock your pool

Swimming Pool Shock should be added to your swimming pool at least once each week, to keep pool water safe and clean. You should shock more frequently if the pool is used heavily, after you receive large amounts of rain, or during extended periods of hot, sunny weather. Shocking, or "super chlorinating", drastically raises the chlorine level for a short time. The chlorine level becomes so high that bacteria or anything organic in the pool water is completely destroyed. This is one of several very important steps in pool maintenance that every swimming pool owner should be familiar with.

Step 1:
Before pool shock is added to your swimming pool water the granular chemical must first be pre-dissolved in a bucket of water. All forms of pool shock are granular and should dissolve relatively quickly. Fill a 5-gallon bucket with water from the pool and slowly pour the granular pool shock into the bucket of water. NEVER add water to a chemical, always add chemicals to water.

Step 2:
Stir the bucket well and agitate the water for one minute or more to dissolve the pool shock.

Step 3:
With the filtration system running, slowly pour the bucket of dissolved shock directly in front of a return line fitting. You will see the water being carried out into the pool by the jet of water coming from the return line. Pour slow enough that all of the water from your bucket is carried out into the pool and does not settle to the pool floor.

Tips
• When you are pouring the bucket of dissolved shock water into the pool and you near the bottom of the bucket (down to about 1/4 left in the bucket), you should fill the bucket back up with water. Stir the bucket of water again for one minute or more to dissolve left over shock granules at the bottom of the bucket, which did not dissolve the first time.

• If you have a vinyl liner in your swimming pool you cannot allow un-dissolved pool shock to settle to the floor, because this may bleach or stain your pool liner.

Warnings
• Always add chemicals to water. DO NOT add water to chemicals.

• The manufacturers of pool shock products suggest that you wear protective goggles and other safety equipment to prevent injury. Follow the manufacturer's instructions on the packaging closely.

• Swimming in water with too much chlorine is very dangerous. Wait until the water reads 3ppm or less.

What is pH ?

pH and total alkalinity are related. It is not possible to change one without changing the other.

Total alkalinity is the buffering capacity of water. It is also its resistance to change in pH. Too high Total alkalinity and the pH is hard to change. It is also defined as water’s ability to neutralize acid. Too low Total alkalinity and the pH changes every time any chemical is added.

The proper Total alkalinity depends on the sanitizer you are going to use. Here are the proper Total alkalinity levels for some sanitizers:

Gas chlorine, trichlor, bromine tabs – 120 – 140 ppm
Dichlor, ozone, 2-part bromine or a combination of 2 type of chlorine: 100 – 120 ppm
Cal hypo, lithium hypo, liquid chlorine: 80 – 100 ppm

You use liquid or dry acid (Muriatic which is 31.45% hydrochloric – HCl or sodium bisulfate) to lower both pH and Total alkalinity. Most people use Muriatic. You can use dry acid and 2.5 pounds are equal to 1 quart of liquid.

Remember this about pH:

1. The pH scale is logarithmic meaning that 1 whole number on the scale is a factor of 10. Therefore, it will take 10 times more acid to lower the pH from 9.0 to 8.0 than it does to lower it from 8.0 to 7.0.
2. If the Total alkalinity is very high, the acid will work first on the Total alkalinity and then the pH.

You use sodium bicarbonate (baking soda) or sodium carbonate (soda ash) to raise pH and Total alkalinity. Which one you use depends on whether you want to raise both pH and Total alkalinity or just raise Total alkalinity with a small rise in pH.

If you want to raise both pH and Total alkalinity, use soda ash.

If you want to raise Total alkalinity with a small or little rise in pH, use sodium bicarb.

The reason is this: Soda ash has a pH of 13 and it contributes to Total alkalinity. Because of its high pH, it will raise pH substantially. On the other hand, bicarb only has a pH of 8.3. Therefore adding even a lot of it will raise Total alkalinity with a small effect on pH.

You can easily determine how much acid or base to add to your pool by using the Acid Demand or Base Demand test in your test kit.

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