Learn which plants thrive in your Hardiness Zone with our new interactive map!

How to Check Phosphates in Pool Water

By Marshal M. Rosenthal ; Updated September 21, 2017

Algae formation in a pool fouls the water’s filtration system as well as increasing the level of bacteria present. High levels of phosphates, brought into the pool’s water through dust, leaves and even rain water, contribute to the growth of the algae. You can check the level of phosphates in the water using an electronic digital water analyzer. The device, which will provide a reading of the level of phosphate in the water, is available from pool supply centers as well as some spa shops. The digital water analyzer does not require any specialized knowledge of chemistry in order to use.

Step 1

Open the battery compartment lid on the back of the digital water analyzer. If a screw is on the lid, loosen the screw first with a Phillips jeweler’s screwdriver.

Step 2

Insert the appropriate battery or batteries into the battery compartment. Close the lid and tighten the screw, if there is one.

Step 3

Add the amount of phosphate reactive agent from the kit that comes with the digital water analyzer into the intake tube on its top. The amount needed is noted in the instruction manual.

Step 4

Scoop up some water from the pool in a paper cup. Pour the water into the intake tube on the top of the digital water analyzer.

Step 5

Turn on the analyzer’s power button. Let the numbers on the LCD display on the front of the analyzer cycle up and down. Write down the number that is displayed once the numbers no longer are cycling.

Step 6

Empty the water from the intake tube onto the ground. Repeat the test again.

Step 7

Add the two numbers together. Divide the results by two. Write this number down to get the average amount of phosphate in the pool water. Measurements now can be taken to decrease the amount of phosphate in the water to the appropriate level.


Things You Will Need

  • Digital water analyzer
  • Phillips jeweler's screwdriver
  • Battery(s)
  • Paper
  • Pencil

About the Author


Marshal M. Rosenthal is a technology maven with more than 15 years of editorial experience. A graduate of Brooks Institute of Photography with a Bachelor of Arts in photographic arts, his editorial work has appeared both domestically as well as internationally in publications such as "Home Theater," "Electronic House," "eGear," "Computer and Video Games" and "Digitrends."