Frequently Asked Questions

The Sustain Pool Care System is the intelligent way to maintain a beautiful, sparkling pool. In addition to the advice presented here, be sure to click on our “Start Blue. Stay Blue. Pool Care Guide” for additional information on the SUSTAIN® 3-Part Pool Care System. Also you can use our Store Locator to find the dealer nearest you.

Click on a question below to take you to the answer:

FAQs

Why should I use the Sustain Pool Care System?

Over 25 years of proven performance has shown that the Sustain 3-Part System provides you with an effective and easy-to-use pool care routine. The use of other chlorine products often results in too little or too much chlorine. Sustain is formulated and designed to deliver chlorine more evenly than conventional pool care chemical systems. Also, as part of this System, Sustain Summer Shield Chlorine Extender is the brain of the program. This product actually holds backup chlorine in reserve, and only releases it when it senses your pool's level of chlorine protection (against algae and bacteria growth) has been depleted. (<1 ppm).

Where can I buy the Sustain Pool Care System?

Click here to locate an Authorized Dealer near you.

How much Sustain do I need for a season?

Click here to determine your pool capacity and product requirements.

Can you provide a basic water balance overview?

Below is a list of the water balance basics that will help ensure that you have a trouble-free pool season:

Basic Water Balance Factors

  • Chlorine (1-3 ppm)
  • pH (7.2 - 7.4 ideal)
  • Total Alkalinity (80-100 ppm)
  • Stabilizer Level (30-50 ppm)
  • Calcium Hardness (200-800 ppm)

Water Balance Basics

  • At the beginning of the season take a water sample to your Authorized Sustain Dealer for complete analysis.
  • Do not start on the SUSTAIN System until all water balance factors have been established.
  • Make sure that all of your equipment is operating properly:
    • Check pump and filter.
    • Make sure the skimmer is unobstructed.
    • Adjust the return jets to minimize dead spots in the circulation of filtered water.
  • Test pool water with a DPD kit or Test Strips once a week (or more often depending on pool use and weather conditions).
  • Take a water sample to your dealer for testing a minimum of every 6 weeks.
  • Run your pump at least 12 hours per day.
  • Follow SUSTAIN product label directions.
  • Never mix chemicals.
  • Don't guess. If you are wondering what to do, visit or call your dealer with problems that are chronic or unusual.

How long should the re-circulation pump be operated?

The Association of Pool & Spa Professionals (APSP) sets guidelines for pump and filter sizing that allow circulation flow to achieve at least two water turnovers per day. Operating your pump for 12 hours per day will ensure one turnover. Good circulation is necessary for filtration and dispersing the sanitizing chemicals throughout the pool water.

Note: Set the return jets to optimize the circulation pattern and to minimize dead spots where algae can bloom. The recommended angle for jets is 45° downward.

How does Summer Shield work?

Summer Shield Chlorine Extender combines with some of the chlorine in the pool water and shields it, thereby creating a reserve tank of chlorine to give extra protection against the development of algae.

As Free Available Chlorine (FAC) is depleted, the shielded chlorine releases into the pool water to control algae and bacteria growth. Sustain Summer Shield Chlorine Extender provides chlorine-killing power despite unpredictable increases in chlorine demand brought on by debris from rain and wind storms; or when your nice quiet swim turns into a full-blown neighborhood pool party.

 

Important Note:  Summer Shield Chlorine Extender is a “good form” of combined chlorine. It is measured by subtracting the Free Available Chlorine (FAC) reading from the Total Chlorine (TA) reading.  Proper application of the Sustain 3-Part system will prevent “bad” combined chlorine (weak, foul smelling water) from forming.  So remember, what is measured as combined chlorine is actually the Summer Shield concentration in water.  (See how do I measure Sustain Summer Shield Chlorine Extender?)

How do I measure the Summer Shield Chlorine Extender in my pool water?

Testing for Sustain Summer Shield Chlorine Extender can be confusing because Shield measures as a chloramine (combined chlorine). Chloramines are usually associated with a strong chlorine odor coming from the water.  Prescribed application of the Sustain system, which includes maintaining a 1.5 ppm minimum dosage of Shield will prevent, “Bad forms” of chloramines from developing.  So the chloramine reading you will get is actually the Shield molecule which function as a chlorine reserve to prevent algae formation. To measure Shield, follow these step:  

 

Water Testing when Using Sustain®

  1. Always use an DPD or 3-Way Test strips to test your water.  Do not use an OTO kit.
  2. Ensure that the water being tested has been correctly Energized or shocked within the last 12-24 hours and that the water has had no heavy bather load since Energizing/shocking. 
    1. 1 cup of Energizer per 5,000 gallons of pool water
  3. Test water for pH, TA, CH, CYA, FAC, and TC (and any other necessary parameters). 
  4. Subtract FAC from TC to get CC (TC – FAC = CC)
    1. CC is the amount of Sustain® Summer Shield in the water sample. 
    2. Maintain Summer Shield Extender between 1.5 and 5 ppm!

What is algae, how do I know I have it, and how do I get rid of it?

The appearance of algae is an indicator of one or more pool water deficiencies. In some cases, the deficiency is obvious, other times you may need to review the basic checklist:

  • Is the pool equipment, pump, and filter operating properly?
  • Is the circulation pattern of the pool water minimizing dead spots?
  • Are the pH and Free Available Chlorine (FAC) in the recommended ranges?

Note:  Often cloudy water can be a precursor to the development of algae as well.  

For detailed information see the Algae section under the “Pool Care” tab.

Will tablets in the skimmer damage equipment?

Equipment damage normally occurs with very high chlorine levels and/or very low pH levels generally associated with the use of 3-Inch white trichloroisocyanurate (or trichloro-s-triazinetrione) tablets ("trichlor" for short).

 

Trichlor tablets are often added to the skimmer and when the pump is off, the chemical continues to dissolve, filling the plumbing with highly concentrated chlorine and low pH water. It is also common to see a bleached liner around the skimmer opening in pools with vinyl liners.

 

The uniquely colored blue 3-Inch Sustain Chlorinating Tablets will not lower the pH and the skimmer dispenser will hold concentrated chlorine solution that might accumulate when the pump is off, thereby safeguarding your pool liner, plumbing and equipment.

(Note: Remember to run your pump for at least 4 hours after adding Shield Energizer Tablets.)

Why do I continually have high chlorine readings?

First, be sure that you are using the right test kit: 3-Way Test Strips or DPD (pink) and not using OTO (yellow). OTO measures total chlorine, so it will always give too high of a reading when the Sustain System is used properly. Free Available Chlorine (FAC) is the form of chlorine that safeguards the swimmers and both DPD (tablets or drops indicate available chlorine with a pink color) and the 3-Way Test Strips measure FAC. If your FAC readings are consistently high, follow these steps:

  1. Adjust the lid on the Skimmer dispenser to a smaller opening so the table erosion decreases.

If the tablet erosion is one tablet per week or less, and you still have high FAC readings, add one-half the normal dose of Shield Energizer (½ cup per week for every 5,000 gallons of water.)

I know there’s free chlorine in my water but my test strip is still white after dipping it into the water. What’s going on?

This is called the “bleaching out effect”. There is more chlorine in your water than the test strip can detect, so it stays white. Diluting your water sample (50% pool water with 50% tap water) might help. If you do this and the new strip turns a color, simply double your test strip reading to calculate your actual free chlorine result.

If you have any questions about your test results, please contact your Sustain dealer for further help.

What can I do to decrease high chlorine readings?

If your Free Available Chlorine (FAC) readings are consistently high, follow these steps:

  1. Adjust the lid on the Skimmer dispenser to a smaller opening so the table erosion decreases.

If the tablet erosion is one tablet per week or less, and you still have high FAC readings, add one-half the normal dose of Shield Energizer Tablets (½ cup per week for every 5,000 gallons of water.

Why won't the tablets in my skimmer cup dissolve?

Low tablet delivery rates are caused by low flow in the skimmer dispenser at the tablet surface. Follow these steps to increase the delivery rate:

Corrective Actions:

  1. Open the adjustable lid to expose the tablets to more water flow. For in ground pools you may want to remove the lid entirely.
  2. Check the water flow in your skimmer. If you think the flow is too slow, check your filter back-pressure and circulation rate at the return jets. You may need to backwash the filter or clean the filter element. With pools that have a main drain, the flow through the skimmer can be increased by decreasing the flow from the main drain, but it's a good idea to consult your pool professional before making this kind of adjustment.
  3. Slow erosion can be caused by the formation of scale on the tablets. This scale is calcium carbonate, and is formed from carbon dioxide pick-up from the air during tablet storage, or by pH and Total Alkalinity (TA) being too high in the pool water. Test the water and adjust if necessary. If this is the case, simply put the tablets directly into the skimmer so they will dissolve. Remember to transfer them into the skimmer dispenser before your pump cycles off. Formation of scale is an indicator to adjust the pH and/or TA.

Preventative Follow-up: 
Test your water weekly and pay particular attention to pH and Free Available Chlorine (FAC). Make additions and adjustments as needed.

Do Shield Energizer Tablets need to be added every week?

The pool should be Energized weekly to reload Sustain Summer Shield Chlorine Extender with reserve chlorine; oxidize any contaminants; and restore and maintain the sparkle to your water. If the pool is lightly used or you live in a cool climate, you may see the Free Available Chlorine (FAC) levels tend to rise above 3 ppm and stay high throughout the week. In these cases, a one-half weekly dose (½ cup per week for every 5,000 gallons of water) will be sufficient.

Why does my filter back-pressure increase?

If you see an increase in the filter back-pressure after adding Sustain Shield Energizer Tablets it shows the pH of the pool water was not adjusted to the target of 7.2 before adding the product. You can make this adjustment after adding the Shield Energizer Tablets simply by adding the amount of pH Decreaser you would have normally added before adding Shield Energizer Tablets. If you don't know how much, try adding 1 pint muriatic acid (or 1 lb dry acid, sodium bisulfate) for every 5,000 gallons of pool water. Remember to pre-dissolve or pre-dilute the acid and walk it around the pool as you add it.

How should I test for chlorine and pH?

A recommended and easy way to test for pH and Free Available Chlorine (FAC) is to use 3-Way Test Strips. The color pads on these strips are quick indicators for pH, FAC, and Total Alkalinity (TA).

Note: 3-Way Test Strips are the most convenient way to test your pool water, but they are sensitive to moisture. Keep the bottle tightly capped.

Another effective method involves the use of a DPD test kit; a more traditional method using vials and reagent drops to measure pool water balance factors.

Either kit may be obtained at your local Sustain dealer.

What is DPD and why is it better than OTO?

The DPD test (pink color) gives more precise measurements of the chlorine levels, free and total chlorine, and is recommended for determining how much Sustain Summer Shield Chlorine Extender is present.

Why can't I use an OTO test kit when using Sustain?

OTO does not clearly show the difference between free and combined chlorine and therefore should not be used when the pool is treated with the Sustain Pool Care System. Sustain Summer Shield Chlorine Extender holds a backup reserve of chlorine that tests as combined chlorine. To avoid confusion, use DPD or 3-Way Test Strips to measure FAC without interference.

Note: DPD test kits use phenol red as the pH indicator. Another test that is useful in testing the pH is the Acid Demand Test. Ask your Sustain Authorized Dealer about this test. It shows how much acid is needed to decrease the pH to the target 7.2 - 7.4 range. Remember when using acid to decrease the pH, dilute it in a bucket of pool water and walk it around the pool, adding it in small increments.

Important: Always begin the swim season with fresh test kit reagents: pH indicator, Acid Demand Drops and DPD. Throw away last year's test strips, or if you're using a standard test kit with liquid reagents, replace the reagent dropper bottles and the entire test kit if the color charts have faded.

What is the ingredient of pool conditioner or stabilizer?

Chlorine stabilizer (pool stabilizer or conditioner) is a chemical known as cyanuric acid (CYA), or s-triazintrione. It is essentially 100% strength. All chlorine is decomposed or broken down by the sun's ultraviolent light. The presence or CYA in your pool water will decrease the rate of chlorine loss due to sunlight. Chlorine will combine with cyanuric acid and become much less reactive to sunlight. A pool stabilized at 30 - 50 ppm cyanuric acid will have from 1/2 - 1/3 the chlorine loss of an unstabilized pool. Since its only use is to protect from sunlight, there is no benefit to adding cyanuric acid to indoor pools.

What's the best way to add chlorine stabilizer or cyanuric acid?

Cyanuric acid (conditioner or stabilizer) is a granular solid that dissolves very slowly in water. If you simply broadcast it into the pool, it will fall to the pool floor and remain undissolved for days.

The simplest way to add the stabilizer is to add it when the pool is up and running, cleaned, and the filter back-washed. Then, slowly add the granules to the skimmer with the pump running. Run the pump continuously (without 3-Inch Tablets in the skimmer) and do not backwash for at least 4 days.

What's the difference between pH and Alkalinity?

While they influence each other, they are different components of your pool water and different tests are required. pH represents the amount of Hydrogen ion in the water. More Hydrogen ion means more acidity and pH is lower. The pH scale is logarithmic, so every pH unit represents a ten-fold change in acidity or alkalinity. The scale goes from 0 to 14, with pH = 7.0 being neutral. Some common household acids include vinegar (pH 3) and lemon juice, (pH 2). Products with higher neutral pHs are eggs (pH 7.8) and household ammonia (pH 10).

Alkalinity or Total Alkalinity (TA) is a measure of the carbonate, bicarbonate and hydroxide ions in the pool water. When the pH is neutral, most of the alkalinity is in the form of bicarbonate ion, which is found in common baking soda. Usually 80 ppm minimum TA provides sufficient buffering capacity to resist change when high or low pH chlorine products are added to pool water. If TA is lower than 80 ppm, the pH will tend to bounce from high to low readings. However, when the TA is 100 ppm or more, there is a tendency for the pH to drift upward. TA is important largely due to its importance to maintaining pH in the proper range.

Why is pH important?

a) Swimmers' comfort is affected by the pH of the water. Most people swim with their eyes open. The pH of tears is about 7.4. Pool water with a different pH will irritate the eyes. So test the pH and adjust to 7.2. The natural tendency while using Sustain tablets is for the pH to increase slowly.

b) The effectiveness of Free Available Chlorine (FAC) is influenced by the pH. As the pH increases, the effectiveness as a sanitizer decreases. For example, at pH = 7.2 the FAC is about three times as effective as the amount would be if the pH = 8.0. For the FAC to be most effective, without swimmers' eye irritation, the ideal range is 7.2 - 7.4.

c) As if providing comfortable and healthy water is not enough, pH is also an important factor in protecting your pool investment. Pool liners, plaster, tile grout, heaters, pumps and metal fixtures are attacked by aggressive, acidic, (you guessed it) low pH water.

My pool's pH is hard to control. Why?

The pH will be difficult to control if the Total Alkalinity (TA) is not in the proper range. TA should be 80-100 ppm. If the TA is less than 50 ppm, your pH will swing from one extreme to the other and seldom be in the proper range. This is know as pH bounce. If TA is more than 100 ppm, pH will drift upward, requiring frequent adjustment and large amounts of acid to lower the pH.

Corrective Action:

a) The best way to adjust pH is to use the Acid Demand Test. Check your test kit to see if it includes this procedure. If you don't have an Acid Demand test, you can get one at your Sustain Authorized Dealer. Remember when lowering the pH to walk the pre-diluted acid around the pool adding it in small increments to the water.

b) If your TA is over 100 ppm, you will want to adjust it downward unless your calcium hardness is <200 ppm. If so, let the TA drift down naturally as the calcium hardness increases slowly. [ More info...]

Prevenative Follow-up:
Test your water weekly and pay particular attention to pH and FAC. Make additions and adjustments as needed.

What chemicals are typically used to lower pH?

The most common chemical used to lower pH is liquid Muriatic Acid. Other chemicals include: Sulfuric Acid and dry Sodium Bisulfate. (All of these products can be used to lower Total Alkalinity (TA) as well.) Axiall recommends a pH range of 7.2 – 7.4. Ask your Authorized Sustain Dealer which product he recommends and always follow manufacturer’s label directions when applying any pool chemical. Never mix pool chemicals together.

What chemicals are typically used to raise pH?

The most common chemical used to raise pH is Sodium Carbonate. Axiall recommends that you maintain your pH range at 7.2 – 7.4. Ask your Authorized Sustain Dealer for his recommendations based on a professional water test and always follow manufacturer’s label directions when applying any pool chemical. Never mix pool chemicals together.

What chemicals are typically used to raise Alkalinity?

The most common chemical used to raise pH is Sodium Bicarbonate. Axiall recommends that you maintain your Alkalinity at 80-100 ppm and a pH range of 7.2 – 7.4. In cases of very soft water (<200 ppm Calcium Hardness) or very high hardness, the TA can be adjusted above or below this range. Ask your Authorized Sustain Dealer for his recommendations based on a professional water test and always follow manufacturer’s label directions when applying any pool chemical. Never mix pool chemicals together.

How do I decrease Total Alkalinity without decreasing pH?

With pH and Total Alkalinity, it is difficult to decrease one without affecting the other. Liquid acid (muriatic acid or HCl) or dry acid (sodium bisulfate) is used to decrease both pH and Total Alkalinity (TA). To adjust one or the other, use the appropriate technique:

  • To maximize the effect on pH, you walk it, or add small amounts several places around the pool.
  • To maximize the effect on TA, you slug it, or in other words, add it all in one place.

To decrease TA, the best time to add the acid is when the pool water is not circulating. Dilute or pre-dissolve the acid in a bucket of pool water before adding it into the deep end. Allow at least one hour before starting the pump. Allow to circulate overnight before further testing and making more adjustments.

How do I decrease pH without decreasing Total Alkalinity?

With pH and Total Alkalinity, it is difficult to decrease one without affecting the other. Liquid acid (muriatic acid or HCl) or dry acid (sodium bisulfate) is used to decrease both pH and Total Alkalinity (TA). To adjust one or the other, use the appropriate technique:

  • To maximize the effect on pH, you walk it, or add small amounts several places around the pool.
  • To maximize the effect on TA, you slug it, or in other words, add it all in one place.

To decrease TA, the best time to add the acid is when the pool water is not circulating. Dilute or pre-dissolve the acid in a bucket of pool water before adding it into the deep end. Allow at least one hour before starting the pump. Allow to circulate overnight before further testing and making more adjustments.

Why did my pool turn cloudy?

Why did my pool turn cloudy?

There are a variety of reasons why this can happen. For causes and remedies see the Cloudy Water section under the “Pool Care” tab.

What is the blue color in the tablets and shock?

The color is a small amount of dye added to the products. They are readily dispersed into the water having no effect on clarity. The colorants are added for safety reasons. Mixing of chemicals can be dangerous. The blue color is added to clearly distinguish Sustain from other products.

Never mix other chemicals with Sustain Blue tablets.

What are the white, floating particles and how do I prevent them?

The particles are a calcium carbonate residue that contains enough trapped air to float. These particles are common and are usually drawn in by the pump and trapped in your filter. They are completely harmless and easily dispersed using your hand or the leaf skimmer.

Corrective Action:

  1. Check to see that the weir flap (skimmer flap) on the skimmer is functioning properly, which will prevent any skimmer residue or other debris from returning to the pool.
  2. The flow rate through the skimmer may be slower than normal. Check your filter back-pressure and backwash or clean your filter element if needed.
  3. You may need to increase the flow through the skimmer by decreasing the flow from the main drain, but it's a good idea to consult your pool professional before making this kind of adjustment.

Preventative Follow-up:
Routine inspection will be sufficient, along with maintenance of proper skimmer action.

What is scale and how do I remove it from pool surfaces?

Scale is typically calcium carbonate. It usually forms first on the tile or coping at the water line. Follow these steps:

  1. Test the pool water for pH, Total Alkalinity (TA), Calcium Hardness (CH) and compare the results to the recommended ranges.
  2. Apply a dilute solution of vinegar (1:1) or dilute muriatic acid (10:1) directly to the scale to dissolve it.
  3. Adjust TA and pH after the scale has been removed to ensure it doesn't form again. Note: If the pH is low, allow 24 hours for it to recover and test again.

Preventative Follow-up:
Maintain water balance, keeping primarily pH and total alkalinity in the proper ranges.

Why does the water turn colors, and why do stains occur?

If there are metals dissolved in the water, the addition of shock products can turn the water colors and/or stain the pool surfaces because they oxidize the metals. The main types of metals found in pool water are iron and copper:

  • Iron is often present in the fill water. It will give the water a greenish or yellow cast, then will turn rust colors. This generally occurs in the spring when opening the pool, as a lot of fresh tap water is added, or if the pool is operated with the pH too low (<7) for a long time. Low pH will lead to corrosion of the equipment and fixtures.
  • Copper can be present in the pool water due to corrosive water (low pH) or if copper based algaecides are overdosed. Copper generally gives the water a greenish or blue cast. When dissolved copper is oxidized it will usually form a black stain on the pool surfaces. Chlorine will oxidize the metals in the water and result in colored water and/or stains. Operating the pump/filter system continuously will filter out these fine particles of oxidized metals and may help prevent staining. If the water has color when you are opening for the season or after adding a lot of fill water, take a sample to your Sustain Authorized Dealer and check for metals content. Use a metal removed prior to shocking the pool and circulate continuously.

How do I restore the pool surfaces and prevent discoloration?

For most pools either algae or metals cause surface discoloration. A variety of metals such as iron and copper can be present in the fill water, and of course, copper is a common ingredient of algaecides. As metals are oxidized, they become insoluble and form stains on the pool surfaces, much like the iron stains sometimes seen in bath fixtures and associated with well water. The first thing to do is make sure you have stains and not algae. If the color brushes off partially or completely, it's algae

If it's a stain, follow these steps:

  1. Check the pool water balance. Collect a sample of water and see your Sustain Authorized Dealer. If possible, test the hardness, total alkalinity, pH and cyanuric acid yourself. Unless you're using a copper-based algaecide or adding well-water to your pool, the stains are due to the water becoming aggressive or corrosive. Have your water tested for the presence of metals.
  2. The first thing you'll add to your pool water is a good sequesterant or chelating agent, available at your Sustain Authorized Dealer. Use of a metal remover product will prevent more staining and help transfer the metals that have deposited on the pool surfaces to the filter media.
  3. Continuous circulation is important during this stain removal process. Remember that brushing the stains is necessary to help remove them. (In extreme cases, direct application of acid may be necessary, but leave this to the professionals.)
  4. While the pool is circulating, you'll want to bring the water back into balance. As you increase pH and alkalinity, do it slowly to minimize the staining that can occur.
  5. After the stain is removed and the water is properly balanced, backwash your filter, or if you have a cartridge filter, clean the filter element to ensure the removal of any metals that may have collected there.

What is the best way to close my pool?

See the "Pool Closing" section in the Pool Care guide. If you live in warmer climates, please click here.

How should I store Sustain products?

Store in a cool, dry and well ventilated place. The main ingredient in Sustain Tablets and Shock is Calcium Hypochlorite, a chemical that has been widely used in pool water disinfection since the early 1900s. Calcium Hypochlorite is an inorganic chemical. It is an oxidizer and will decompose slowly over time. This decomposition liberates oxygen and heat. In a cool, dry place this heat will not build up, but in a hot storage shed, the higher temperatures will lead to premature loss of strength. If the product gets wet it loses strength faster. In fact, contaminating Calcium Hypochlorite with organic liquids (such as algaecides) or carbonated beverages can result in a fire, cause an explosion, or release toxic fumes. Always secure the lid after use.

 

Storage Tips:

  • Always store chemicals in their original containers with lids tightly sealed.
  • Keep chemicals in a cool, dry area away from flammable materials, acids, and cleaning compounds.
  • Organize your household, automotive and garden products that are stored in the same areas as your pool chemicals to minimize the potential for fire in the event that a spill occurs. For example, never store paint, antifreeze, algaecides or pool acid on top of (or directly above) your Sustain products.
  • Never mix two different kinds of chemicals.

Can I use pool chemicals left over from the previous season?

If they are Sustain products and you have stored them in a cool, dry area, yes.

Why do I have continually low chlorine readings?

This is usually caused by a low stabilizer level in your water, not enough chlorine delivery, or both. This problem can be addressed through one or more of the following:

  • Check your stabilizer level. It should be between 30-50 ppm. Stabilizer slows down the degradation of chlorine exposed to ultraviolet rays from the sun. Low stabilizer levels can contribute to low chlorine readings.
  • Once it has been determined that the stabilizer level is within range (30-50).
  • Shock with Sustain Shock Treatment according to label directions to quickly establish a chlorine reading between 1-3 ppm.

You can also Increase chlorine delivery by one or more of the following actions.

  • Increase the opening on the adjustable 3” Sustain Blue tablet cup dispenser, or remove the lid altogether.
  • Increase water circulation time to add more chlorine through the skimmer cup. Miminal ciruclaton time should be 12-hrs. per day.
  • For inground pools, increase the flow through the skimmer by opening valve fully decreasing flow through main drain.

If these actions to not eleviate the problem, take a water sample to your Authorized Sustain dealer for testing.