Phosphates

Are phosphates really a problem in swimming pools?

The subject of phosphates can create controversy and lots of lively discussion at the distributor counter. Some will tell you that high levels of phosphate can lead to water quality issues such as resistant algae growth. Others state that it really doesn't matter if there are phosphates in the pool as long as you keep all your chemical levels right.

So what's the real truth?

Let's take a look at this together to find out. Phosphates are biological building blocks that are formed when phosphoric acid comes in contact with certain metals. Most of the natural sources are found in rivers, lakes, and ocean, or mined rock. The United States is one of the largest producers of phosphate from mining. Phosphates are used in detergents, hair care products, fertilizers, and even soda pop. Many of the foods we eat contain phosphate, which is a primary nutrient for muscle growth.

There are many ways phosphate can enter the pool water.

The two biggest sources of phosphates in pools come from metal sequestering products, and the tap water supplied by your local municipality. That's right. The water that you use to fill the pool can be a pretty good source of phosphates. This is because many drinking water municipalities use a phosphate based chemical to prevent corrosion of their delivery pipes. It's important to understand that phosphates exist in many different forms. There are combined forms such as polyphosphates or sodium phosphate.

These compounds are used in many of the cleaning agents and chemicals that we use in pools. There are even some of the binding agents for chlorine tablets that contain phosphate compounds. Not all types of phosphate can be used by algae as a nutrient.

So what happens when phosphate ends up in the pool water? Some say that phosphates aren't a problem in a well maintained pool. Others claim they are the determining factor of an algae outbreak. The truth is somewhere in between, and it's important to understand how phosphate can make the maintenance of the pool a real problem.

Phosphate is one of the prime ingredients in fertilizer. We use fertilizer to help plants grow, and algae is a plant. There are three main ingredients that algae need to grow, nitrates, carbon dioxide, and phosphates. Of these, the only one we can effectively control and remove is phosphate.

Scientifically, phosphate is categorized as a growth limiting nutrient. What that means is that the growth of algae is limited if it can't obtain phosphate, even if there is nitrate and carbon dioxide present. So those that say phosphates are not a concern as long as the water is balanced and chlorinated are correct. But what if the dog and ten kids have a pool party?

What if your pH spikes up?

What if your CYA is over sixty parts per million?

Will you have enough chlorine chlorine in the water to prevent an algae bloom? With higher levels of phosphates, algae have more fuel to grow and to turn a pool green quickly. With the strong nutrient phosphate within the cells, the algae will be much more difficult to kill using chlorine and algaecide. Even in well maintained pools, you can see an increased chlorine demand from high phosphate levels. Now while they do not directly reduce chlorine, phosphates are the prime nutrient for the transition of algae from the spore to the blooming form.

As this process occurs, more chlorine is needed to fight the growth of the algae, even though it's not visible as an algae bloom. This is also what causes the need for an increased output of free chlorine from salt chlorine generators. Phosphates can be tested for, and they're measured in PPDs. That's parts per billion.

Whether you have a salt water system or a regular pool, phosphate levels should be kept below five hundred ppb, ideally two hundred ppb. As stated earlier, phosphates can be present in many combined forms. In pool water, all combined forms will end up as orthophosphates or what we call free phosphate. So when we test for phosphate in the pool industry, we are testing for ortho or free phosphate.

Free orthophosphates are the only form that algae can utilize as a nutrient. HASSA has two great phosphate remover products to deal with the removal and maintenance of free orthophosphate. Fosout works great for pools with levels of six thousand PPB or less. Fosout Plus works to remove high levels of phosphate, removing up to ten thousand PPB in ten thousand gallons of water.

Hey, this is Terry with HAASA. If you have any questions about phosphates, metal stains, or any other water chemistry, please feel free to contact us at w w w dot haasapool dot com, or check out some of our other videos on YouTube, Facebook, and LinkedIn.

Thanks.