Phosphates – Why Do We Care?

All this talk about phosphates in pool water, but what does that actually mean? Let us shed some light on phosphate and how it impacts your pool water balance.

Phosphates Explained

Technically, phosphates are salts of phosphoric acid. Phosphoric Acid is the acid produced when phosphates are dissolved in water. Phosphates, chemical compound PO43-, are plant nutrients that can also be a pollutant.

Sources of phosphates include fertilizers, skin, plant debris, dead bacteria or algae, traces of feces carried by pool users, body fluids, rainwater, soil, fill water, and bird droppings.

Bottom line: Phosphates in pool water contribute to algae blooms.

Phosphates and Pool Algae

Phosphates are the limiting nutrient for algae growth. The greater amount of phosphate present in water, the greater amount of inhibitory product, i.e. sanitizers and/or pool algaecides, needed to prevent algae growth. The amount of phosphate present in a body of water will also determine how much algae can be grown. The greater amount of phosphate, the greater potential for algae growth and the severity of the bloom.

To test the phosphate level in your pool water, we recommend using a phosphate test kit like this one from Natural Chemistry.

How to Prevent Pool Algae

The best preventative approach to correct the root cause of algae growth is to stop the input of one select nutrient: phosphates. The removal of phosphates in products such as laundry detergents, soaps, and dishwasher detergents in North America has helped prevent unnatural algae growth in lakes and rivers.

We can do the same in our swimming pools by adding a PHOSfree product that will reduce phosphate levels in pool water. This process will easily and effectively bring the phosphate level to near zero without disturbing the appropriate chemical balance in pool water. At these levels, the nutrient-starved algae are easily controlled with normal sanitation.

Prior to Testing and Treatment

  • Ensure there are no live algae in the water – including the pool filter, skimmer, etc.
  • If there are live algae, treat with shock and/or pool algaecide
  • Pool water must be balanced and chlorine level under 5ppm
  • A clean pool filter is recommended

Recommended Phosphate Removers


Natural Chemistry PHOSfree brings phosphate levels to near zero and should be used when you first begin your phosphate management program. PHOS-free is non-toxic and will not cloud pool water. It is added directly to the skimmer and is compatible with all types of swimming pools, filters, and sanitizers.

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Pool Perfect + PHOSfree

Natural Chemistry Pool Perfect + PHOSfree is a weekly maintenance product that uses enzymes to remove phosphates and non-living organic contaminants from pool water. Pool Perfect reduces the need for maintenance by breaking down organic contaminants, and surface oils and prevents scum lines. It continually cleans the filter media and makes the water feel noticeably softer.

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Pool Magic + PHOSfree

Natural Chemistry Pool Magic + PHOSfree is perfect when opening or closing your swimming pool. Pool Magic uses enzymes to break down organic contaminants and prevent organic staining while the pool is closed for the season. It will continue to keep them under control after the pool is opened.

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Phosphate Remover – Do’s and Don’ts

Do use our PHOSfree products with any sanitizer system including: Chlorine, Bromine, Mineral systems, Ionizers, Biguanide and Salt Systems. Don’t add more PHOSfree than the recommended amount.
Do use our PHOSfree products with any pool filter media: sand, D.E. and cartridge. Don’t add a phosphate remover to a pool with live algae or a pool that is not clean or balanced.
Do swim immediately after applying PHOSfree: it is gentle on the skin, non-toxic and safe for the environment. Don’t add phosphate remover to a dirty pool filter.
Do shake all PHOSfree products to properly mix the ingredients.