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Advice On High Cya Level In Area With Water Rationing


Leo_57

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I recently took a water sample to Leslies and found out that the CYA level is 260. I have discontinued using tablets, and am just using liquid chlorine.

The pool is about 25,000 gallons, plaster, and is about 30 years old. Draining the pool and refilling is difficult due to severe water restrictions in my area.

However, the pool water is clear, there is no algae and I can easily maintain chlorine levels between 2 - 5 ppm. I have not tried to go above 5 ppm as I have a solar cover.

I am considering using the bioactive product, and/or gradually draining and refilling the pool over time to reduce CYA. I should be able to drain/refill more aggressively during winter months when water rationing is less severe and I can use rainwater to help fill the pool.

Water temperature now is low 80s, water temperature will drop into 50s by winter and pool will not be used again until summer, 2017.

Alternatively, I could substantially drain now, but face a very large fine for going way over on my water allocation.

I'd appreciate any advice.

Thanks,

Leo

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You need to understand that the active chlorine (hypochlorious acid) level is proportional to the FC/CYA ratio so your cover will have no problem with an FC higher than 5 ppm when the CYA is as high as your 260 ppm. Even 10 ppm FC with 260 ppm CYA is the same as only 2 ppm FC with 50 ppm CYA in terms of the active chlorine level which is what reacts with the pool cover (and your skin and hair, kills bacteria, prevents algae, etc.).

Unless one of your algae nutrient (phosphate, nitrate) levels is quite low, you could get algae growth at the low FC/CYA ratio. This may not show up at first as visible algae but may be a higher-than-normal chlorine demand as chlorine tries to kill algae faster than it can grow. Then, again instead of visible algae, the water may turn dull/cloudy before it the algae clumps enough to look green. Different algae behave differently in their growth, but green algae often develops in this high chlorine demand --> dull/cloudy water --> green algae bloom sequence.

The BioActive product is very hit-and-miss, mostly a miss. It's very hard to control the bacteria growth (with its enzymes) especially when chlorine is present.

I suggest you keep your FC higher to keep the FC/CYA ratio reasonable (above the level where you notice unusual chlorine demand or water not crystal clear) and over time dilute your water to get the CYA lower. I presume you may get winter rains in your area so should definitely use those to help dilute the water.

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Thanks so much for your reply. This is very helpful.

My phosphate level is 300 ppm. May I ask if I should I reduce this level?

Thanks again!

You need to understand that the active chlorine (hypochlorious acid) level is proportional to the FC/CYA ratio so your cover will have no problem with an FC higher than 5 ppm when the CYA is as high as your 260 ppm. Even 10 ppm FC with 260 ppm CYA is the same as only 2 ppm FC with 50 ppm CYA in terms of the active chlorine level which is what reacts with the pool cover (and your skin and hair, kills bacteria, prevents algae, etc.).

Unless one of your algae nutrient (phosphate, nitrate) levels is quite low, you could get algae growth at the low FC/CYA ratio. This may not show up at first as visible algae but may be a higher-than-normal chlorine demand as chlorine tries to kill algae faster than it can grow. Then, again instead of visible algae, the water may turn dull/cloudy before it the algae clumps enough to look green. Different algae behave differently in their growth, but green algae often develops in this high chlorine demand --> dull/cloudy water --> green algae bloom sequence.

The BioActive product is very hit-and-miss, mostly a miss. It's very hard to control the bacteria growth (with its enzymes) especially when chlorine is present.

I suggest you keep your FC higher to keep the FC/CYA ratio reasonable (above the level where you notice unusual chlorine demand or water not crystal clear) and over time dilute your water to get the CYA lower. I presume you may get winter rains in your area so should definitely use those to help dilute the water.

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