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Phosphates & Nitrates: Stopping Algae Growth Before It Starts

Categories: How To Guides, Chemicals, Maintenance & Upkeep
Before we talk about Phosphates or Nitrates we need to talk about algae. Algae is a known opponent for any pool owner. Like most living things, algae only requires a few simple things to thrive and grow:
  • Water
  • Sunlight
  • Oxygen
  • Food
Since we can’t do a thing about oxygen, water or sunlight we control what we can: their food supply. What is their food supply? All the various forms of phosphates and nitrates floating around in your pool. See, phosphates are often the neglected piece of the puzzle that is pool chemistry. A pool owner may struggle with periodic algae blooms in spite of their consistent chlorine and conditioner routines. Controlling phosphate levels in addition to this is the key to combating the problem, grant forgiveness for occasional chemistry neglect, and fight algae growth at its root.
What are Phosphates Exactly?
Yes phosphates are what the algae in your pool are feeding on.The more food algae has the quicker it is able to grow and multiply. Combine this with the right shade and weather conditions and you will find yourself with rapid growth. Keeping all phosphates out of your pool is nearly impossible, but here short list of Phosphates sources are:
  • Soil & Fertilizers that are usually blown in by the wind or via your sprinkler system.
  • Freshwater fed by your water leveler
  • Any plant material like twigs and leaves.
  • Soap, detergents and hygiene products on swimmers.
  • Chemicals containing phosphoric or phosphorous based components. Usually this is found in metal removers and sequestering agents.
As these phosphoric materials breakdown in your pool they become digestible by the algae. Ideally you want to keep the phosphate levels in your pool between 100-125ppb (parts per billion). The higher the phosphates levels the more difficult it becomes to remove algae as it grows more and more resistant to shock and sanitizers.
What about Nitrates?
Nitrates are another food source for algae. Having nitrates in your pool in less common but also much less treatable than phosphates. Unfortunately there is not a chemical on the market that can remove nitrates from the water. If levels get too high it will lock up the chlorine in your pool and pretty soon there will be algae growing. When this happens the best course of action is to drain and refill the pool. Draining is never a fun task so the old adage: “an ounce of prevention is worth a pound of cure” is the key strategy against this. A pool owners should do their best to avoid these common sources to keep nitrate levels low and manageable:
  • Fertilizer (the most common source)
  • Birds (usually ducks) passing over or bathing in the pool
  • Rain spill off from trees hanging above the water
  • Human waste and sweat
Note that a nitrate is a plant nutrient and, though common outdoors, is not going usually an issue unless your pool suffers excess exposure to these sources.
What to do about Phosphates?
Since it is impossible to keep phosphates out, the best course of action is to get your pool on a program of phosphate removers. Such a program keeps the phosphates levels at a harmless range and kicks the legs right out from under algae.
Pool Perfect + Phosfree is the perfect tool to get your phosphate levels in check as well can keep your water clear.
Using this product is simple:
  1. First the pool should be CLEAR of algae growth (keep in mind this is NOT an algae remover but a prevention method). Use a regiment of shock to get the water cleared up.
  2. Test the water and ensure the sanitizer level in the pool is below 5ppm (parts per million)
  3. Backwash and or clean your filter to ensure effectiveness.
  4. Shake well
  5. Add to your skimmer while the pool is circulating. It is recommended to use one capful per 8,000 gallons of water in your pool.
  6. Test water and reapply Phosfree is the phosphate levels are still high.
Phosefree is able to remove up to 900ppb in one use. Once the pool’s phosphates levels are in the proper range then a weekly or bi-weekly maintenance course can begin. If you phosphate levels exceed 900ppb it is recommended you use the commercial grade Phosfree.
Another option for combating is the Orenda Technologies Phosphate Concentrate or Phosphate & Enzyme Remover. Orenda's potent concentrate can remove up to 10,000ppb per 10k gallons of water. This products application is similar to Phosfree and is also safe and non-toxic.
Regardless of what you use for your Phosphate maintenance it is recommended you check phosphate levels weekly with a Phosphate Test Kit.
In end, getting your pool on a regiment of phosphate treatment will help keep those algae blooms from ruining your swim season and hopefully save the money you would otherwise need to spend on additional shock and sanitizers!
If you have any questions about combating phosphate and nitrate growth, please give us a call at 888-836-6025 or email us with your questions. 
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Pool Supply Unlimited is an e-commerce company that loves water. We love to pump it, filter it, heat it, chlorinate it, light it up and stare at it while we're barbequing a fat, juicy steak. There are real pool professionals working here. Our guys have seen thousands of pools in their careers, no exaggeration. We are based in San Antonio, TX and can land most products to your door (within the 48 contiguous states) in less than a week.
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