Frequently Asked Questions: Pools

Why do I need to shock my pool every week? 
Shocking your swimming pool is a very important element in maintaining your pool water’s clarity and balance. Using chlorine tablets alone will not kill off all bacteria and algae that grow in the pool water. Also, the chlorine tablets have a very low pH level, and their overuse will lead to a low pH, which is very dangerous to the pool, and its users. By shocking the pool each week, you will be quickly raising the chlorine level, which will rid the pool of contaminants, without lowering the pH of the pool water.
Why is the pH of the water so important?
pH is the measure of acidity in the pool water. pH only ranges between 0 – 14, so even a slight change in the pH of your water can greatly affect various elements in your pool. A pool’s pH should be maintained between 7.2 and 7.6. A low pH means that the water is acidic and will dry out your liner, eat away at any stainless steel and copper parts of your pool, as well as cause irritation to swimmer’s eyes and skin. pH can be easily tested for and is inexpensive to adjust.


Why do I need to backwash? Backwashing your filter removes debris that gets caught up in your sand or DE so that your filter can continue to work effectively in cleaning your pool. Backwashing should be done whenever the filter pressure increases approximately 10 psi over normal pressure, and the water pressure returning to the pool decreases. Follow your filter system’s instructions or contact True Blue for directions on backwashing for the system that you have.

I have a sand filter.  Why is my pool always cloudy?

Sand filters have a difficult time filtering out very small debris because often times the microscopic particles of dead algae and waste are smaller than the grains of sand themselves. A sand filter can also “channel,” causing pockets in the filter where water passes through easily, without going through sand. To prevent this, you need to chemically clean your sand at the end of each season with a designated filter cleaner, backwash frequently throughout the season, and use clarifiers to help the water remain crystal clear.

How many tablets should I use in my pool?

We recommend that 1-2 tablets be used for every 10,000 gallons of pool water. During cooler water temperatures and when the pool receives less use, one tablet per 10,000 is sufficient. During the hottest summer months when pool use is high, 2 tablets can be used for every 10,000, but no more then that should be used. Keep in mind that tablets do have a low pH, so overuse of them can disrupt balancing chemical levels. If there is a large amount of algae in the pool, extra shock can always be added without effecting the pH level.

When is the best time to shock my pool?

You should always shock your pool in the evening, after the sun has gone down. Shock is an unstabilized chlorine that can burn off easily from sunlight, even on overcast days. By shocking at night, you are giving the chlorine a chance to bond with the chlorine stabilizer so that by the time the sun comes out the next day, your chlorine level won’t dissipate as quickly. Also, this gives the pool enough time to react with the high level of chlorine, so that you can usually swim the next day after a pool has been shocked.

How long should I wait to swim after adding chemicals?

Most balancing chemicals, such as pH, alkalinity, and calcium hardness, will become incorporated into the water within an hour of adding them, at which time swimming is safe. Shock takes longer to adjust with the pool water, so waiting overnight after shocking before you swim is recommended.

Why do I need to have my water tested professionally every 2-4 weeks?

Testing at home with your strips or drop test kits give you only a limited reading of your balancing chemical levels of your pool water. The average home test kit only reads pH, chlorine, and sometimes alkalinity. There are various other levels that are important to your pool that need to be tested on a regular basis to ensure water balance and safety for the swimmers. Also, the professional testing done in store is far more accurate than home tests, leaving you with added security that your pool water is safe and balanced.

I’ll be going on vacation for a week.  What should I do to keep my pool healthy while I am gone?

While you are away, it is important that your water circulates and is sanitized. A pump timer and automatic chlorinator are the most foolproof ways of ensuring that this is done, because they will automatically turn your pool on and off each day, and distribute chlorine into your water. If a timer and automatic chlorinator are not an option for you, having a neighbor stop by once every day or two to run the pump and check on chemicals will help to keep your water healthy while you are away.

What is the difference between HTH and other chlorines?

HTH is a calcium based product, which means that although it can be very effective in killing off contaminants in your water, it can also lead to some problems long-term. The high level of chlorine in HTH can more rapidly bleach out liners and bathing suits than other chlorine products. Also, with long-term, high usage of HTH, the pool can develop calcium buildup, which would lead to calcium scaling inside of the filter and in the lines of the pool. This scaling ultimately causes damage to your filtration system, and can be avoided by using HTH in limited amounts, or by using other types of chlorines.

Why am I getting DE back in my pool?

Getting DE back into a pool is an indication of some type of problem within the filter itself. Although it could simply be a matter of using too much DE after backwashes, more often it means that a part inside the filter needs to be replaced. If you have a grid system DE filter (most inground pools have this type), it could mean that the spider gasket in the multiport needs to be replaced, that the grids inside the filter are torn, or that the manifold, which holds the grids together, has cracked. Filters with “fingers” (most aboveground systems and some older inground systems) could be torn, the diaphragm gasket may need to be replaced, or the tube sheets may have cracks in them. Check your filter carefully to make sure that all parts are in good condition, and replace necessary parts. True Blue also offers a “Clean, Soak, and Inspect” service on filters. This includes cleaning the filter elements of large debris, soaking them for 24 hours in a chemical solution, and inspecting all parts by hand.

What is the difference between Clorox and liquid shock?

Liquid shock is 12.5% sodium hypochlorite. Clorox bleach is 3% sodium hypochlorite. Although they are made of the same chemical, the percentage of chlorine in shock is much greater than Clorox bleach. To treat a 20,000-gallon pool, you would need to use two bottles of liquid shock. To achieve the same amount of chlorination with bleach, you would need to use eight bottles. Additionally, Clorox bleach contains added detergents, which could interfere with the chemical balance of your pool.

Can I use baking soda to raise the alkalinity of my pool?

Baking soda is similar to the chemical that is used to raise the alkalinity of the water, and will give you the same rise that alkalinity powder will. However, baking soda is a much larger granule, and will cloud up the water if used in great amounts. If you need to raise the alkalinity of your pool slightly, with one or two pounds of alkalinity powder, it is usually safe to use baking soda. However, if your water balance requires a significant increase, it is recommended that actual alkalinity increaser be used, as it is a finer granule and will rarely cloud the water, even if used in considerable amounts.

Can I apply chemicals through the skimmer?

Most swimming pool chemicals are not recommended to be applied directly through the skimmer. Shocks are a very strong concentration of chlorine, and if applied directly through the filter, can cause damage to the pump and filter as they pass through in such great concentration. In addition, granules that are not dissolved by the time they return to the pool can sit on the pool floor and bleach the liner. Another chemical that should never be applied through the skimmer is calcium hardness as it heats up when mixed with water and could cause damage to your filtration system and liner. Always follow the directions given to you by your sales associate when applying chemicals to your pool, to be sure that no damage is made to your valuable pool items!

Comments are closed.