Water Chemistry Balance and Optimum Levels

slightly green poolAll pools, whether they are vinyl liner, gunite or fiberglass, even aboveground pools, need maintenance and water chemistry balancing. Water that is not balanced will affect swimmer comfort, and your pool surface and equipment. Many of the readings of your water balance should be taken every few days, with others needing attention on a monthly basis. We’ll cover some of those here.

Remember, clear water does not mean balanced water. You have to check this often.

Water Chemistry

Proper water balance is the single most important factor to maximizing the life and appearance of any swimming pool. The following table shows ranges for basic water chemistry.

Factor Range Frequency
pH 7.2-7.6 Daily
Free Chlorine 1.0-2.0 Daily
Total Alkalinity 80-120 ppm Weekly
Calcium Hardness 200-300 ppm Monthly
Stabilizer 35-60 ppm Monthly

PH Levels
PH is the measurement of acidity of water – measured on a scale of 0 to 14 with 7 being neutral. A pH below 7.0 means the water is very acidic, as the pH approaches 8.0, the water becomes very basic (alkaline).

Not only do proper pH levels allow the other chemicals to do their work, but it is important to note that low and high levels can cause damage to a vinyl liner. Under the right circumstances with pH below 7.0, the liner can actually grow and develop unsightly wrinkles. High pH greatly accelerates the aging process and shortens the life of the liner.

Chlorine is much less effective at higher pH levels. At a pH of 8.0; chlorine is only 22% effective.

Use pH+ or pH- to adjust the pH of your water. Always address the Total Alkalinity level first as it can cause the pH level to fluctuate.

In a pool that has water chemistry problems with pH will create small thin wrinkles in a liner pool. We refer to those as pH wrinkles. There is no way to remove them besides installing a new liner.

Total Alkalinity
Alkalinity is a measuring of the alkaline materials dissolved in water. With the alkalinity in the range of 100 to 150 PPM it helps pH to resist fluctuations. If the alkalinity is low the result is “pH bounce” in and out of range.

Pools with an alkalinity problem often coupled with a pH problem will see issues with the heater core. When these are out of balance water becomes aggressive, and will corrode the inside of your heater core (which contains copper – so if you have copper in your water and have no other source, it’s most likely from your heater). If this happens, you want to remedy your water balance problem quickly and you may need to replace your heater core, or in some cases, the entire heater.

Calcium Hardness
Calcium Hardness refers to the amount of dissolved minerals in water. A low hardness can lead to corrosion of pool surface, filter, heater, ladder, ect. A calcium hardness level that is too high causes cloudy water and scaling (white chalky appearance).

Out of Balance Water

  • Eye and skin irritation
  • Staining
  • Unsightly wrinkles in vinyl liners
  • Interferes with the efficiency of sanitizers
  • Corrosion of metals (pump seals, heaters, lights, etc.)
  • Cloudy water
  • Scale build up (white chalky appearance) on pool surface as well as inside filter and heater
  • Pitting and corrosion of gunite/concrete pools

Cloudy Water

Contaminants buildup: When swimmer wastes and other contaminants build up, the result is “combined chlorine”. Shock the pool!!!

Chemical residue: Using a calcium hypochlorite shock such as can result in a residue build up and cloudy water. If the water looks like chalk or milk, it is usually the result of using a lot of calcium hypochlorite shock. To use this type of shock, especially in vinyl liner pools to prevent bleaching of the liner, you must:

  • Fill a bucket about 1/2 full of water
  • Add Shock – do not stir – let sit for a few minutes – pour only the liquid into the pool
  • Discard the residue
  • Do not try to dissolve the residue

You can also use a flocculant or water clarifier to help clear cloudy water. Check your chemicals first. If they are in balance, then use the other methods.

Water Out of Balance: A high pH, high Total Alkaline or High Calcium Hardness will cause cloudy water. Test the water!!

Algae: Algae is a possible cause of cloudy water. Use Algaecide and Shock to remedy.

Poor Filtration: Is the filter system running a significant number of hours every day? Pumps are designed to run 24/7. During the swim season, the filter needs to run a minimum of 10 to 12 hours daily.

Pools With Cloudy Water Or Algae

  • Adjust pH to 7.2-7.6
  • Add algaecide
  • Add shock
  • Add flocking agent
  • Run filter 1 hour – turn off & leave off overnight
  • Next day vacuum to waste

Metals

It is not uncommon to find metals, often called free metals, dissolved in pool water. Usually they come from source water, sometimes they come as a result of the erosion of metal pool fixtures, such as heater cores.

Free metals in pool water can cause staining of pool surfaces and inhibit the performance of water sanitizers. Ideally, there should be no metals in the water: 0 ppm. If metals are detected in your water you will need a sequestering agent to render them harmless.

Metals: The presence of metals in the water such as iron (reddish-brown), copper (blue-green) or manganese (brown-red) can cause cloudy water. To remove the metals:

  • Obtain Ferri-Iron Tabs and add to your skimmer
  • Run filter 48 hours
  • Run backwash cycle on sand filter as needed

Adding Water Balance Adjustment Chemicals

It is best to pre dissolve a water balance adjustment chemical in a plastic bucket of pool water. Then add to the deep end of the pool or in front of a return with the pump running.

  • pH Adjustment: Add recommended dosage, wait several hours and test water again.
  • Alkalinity: Add at the rate of 5 lbs or less; wait about 10 minutes between each 5 lbs.
  • Hardness: Add at the rate of 5 lbs. Or less; wait 30 minutes between each 5. If large amounts of calcium are needed, add over several days.
Issue Solution
Low pH and High Alkalinity Adjust Alkalinity first, then
the next day adjust pH
High pH Low Alkalinity Adjust pH first, then the
next day adjust Alkalinity
Low pH and Low Alkalinity Adjust pH first, then the
next day adjust Alkalinity
High pH High Alkalinity Adjust Alkalinity first, then
the next day adjust pH

Chlorine Stabilizer (100% Cyanuric Acid)
Stabilizer acts as a sun shield to extend the life of chlorine up to 3 1/2 times. It actually holds the useful form of chlorine in the pool water until needed giving longer protection against bacteria and algae. It leaves no residue – 100% soluble. “Stabilized” chlorine products (sticks – tablets – chlorine powder) contain some cyanuric acid which helps to maintain the proper level throughout the season.

Adding stabilizer
With clean pool – backwash filter. Make a slurry of stabilizer and water, then add very slowly through the skimmer with the pump running continuously for at least 48 hours. Do not backwash for 3 or 4 days after adding stabilizer

Pool Maintenance

Testing Water

  • Follow test kit instructions (test strips are easier to use than kits)
  • Use fresh reagents – shelf life for liquid reagents is only one year.
  • Rinse out test cell with pool water before using.
  • Retrieve water sample at elbow depth from deep end of the pool

Most Important Pool Side Tests: Free Chlorine – pH – Total alkalinity — Free chlorine is the unused, effective chlorine that you want in your pool. — pH a number of influences can bring out rapid shifts in the pool’s pH These include:

  • Rain
  • Swimmer wastes
  • Refill water
  • pH of various pool chemicals
Chemical pH Level
CAL HYPO pH 11.7
SODIUM HYPOCHLORITE pH 13
BROMINE TABLETS pH 3.6
SODIUM DRICHLORO pH 6.0
LITHIUM HYPOCHLORITE pH 10.5
CHLORINE TABLETS pH 2.9
CHLORINE GAS pH 2.0

 

Algae

Mustard Algae: Common algae in pools appears yellow-brown or “mustard” colored. It brushes off the walls of the pools easily, but quickly returns. It often rows in shady areas with poor circulation. It resists chlorine and shock treatment.

Solution: Use an algaecide along with chlorine shock. Follow label directions. Place all vacuum equipment – hose, head, pole, brushes, etc. into pool during treatment Maintain a higher than normal chlorine reading for 4 to 5 days after treatment.

Green Algae: Green algae is one of the most common problems for pools. It usually appears in corners or other areas where circulation is poor. Once established, green algae can grow explosively.

Solution: Use Algaecide along with chlorine shock.. Follow label directions. It is also recommended to use a flocking agent, always vacuum to waste or drain (not backwash).

Black Algae: A very resistant form of algae that clings to the pool’s walls, floor, and cracks. The longer black algae are present, the longer it will take to get rid of it. Black algae can actually pit the mar cite finish in a gunite pool. Treat black algae as soon as it is detected. Black algae are usually found in gunite/concrete pools.

Solution: Brush algae spots vigorously with a stiff algae brush and pour algaecide along the sides where spots are visible. Run filter continuously for one hour, and then add chlorine shock to the pool. Turn off filter and leave off for several days.

Preventing Algae

Task Frequency
Brush walls and pool floor Weekly
Vacuum pool Weekly
Use a maintenance dose of Algaecide Weekly
Use a maintenance dose of Majestic Blue Weekly
Maintain a proper chlorine reading Daily
Keep properly balanced – recommended readings:Free Chlorine:1.0-2.0, pH:7.2-7.6, Total Alkalinity:80-120ppm, Hardness:200-300ppm, Stabilizer35-60ppm Weekly