High CYA and Drought Rules: Your Options for Pool Water

Why is high CYA a drought problem?

The usual fix for high cyanuric acid (CYA) is to replace some pool water. Swim University says, “The only reliable fix for high CYA is dilution.” In a drought, cities may limit draining and refilling pools. That puts owners in a bind.

High CYA slows chlorine. Swim University calls it chlorine lock. The test shows chlorine, but water can still turn cloudy or green. Our post on why chlorine disappears in Texas heat explains the balance.

What do city drought rules say?

City rules differ, and they change. These facts are as of October 2026, from the city pages linked in the sources.

For Euless, the page lists Stage 1 below 75 percent, Stage 2 below 60 percent and Stage 3 below 45 percent. At 81 percent, the page says residents are not under any restrictions but are strongly encouraged to conserve water.

I did not confirm drought rules for other cities, including Grapevine. Check your own city’s water conservation page on the day you plan to drain. See your city on our service areas page.

What can I do without draining?

Try these steps, in order.

1. Test first. Get a reliable CYA reading. Some test strips cannot read accurately at high CYA, per Swim University. A drop test kit or a lab test is better.
2. Stop stabilized chlorine. Tablets and powders add CYA. See trichlor and dichlor.
3. Use unstabilized chlorine. Swim University says to use liquid chlorine if CYA is chronically high.
4. Raise free chlorine to match CYA. Swim University says free chlorine should be about 7.5 percent of CYA. At 100 ppm CYA, that means 7.5 ppm. Follow the product label and safe handling.
5. Hold a steady level of water. Do not let the pool run low. Top off if your city allows.
6. Plan a partial drain for when rules allow. Dilute in steps. Rebalance pH, alkalinity and chlorine after each refill.

Swim University says CYA reducers exist but results are mixed. They work slowly, sometimes taking a week or more, and many pool owners report no change. I would not count on one.

How much water must I replace?

Swim University’s rule of thumb: if CYA is 10 percent too high, remove and replace about 10 percent of the water. The table applies it.

The percentages in the table are my calculation of the dilution math. Swim University gives the 10 percent rule only. A pool also loses some CYA to splash-out and rain over time. A technician can plan a drain and refill that fits the rules.

What if I have a salt pool?

Salt pools run higher CYA on purpose. Swim University lists 60 to 80 ppm for an outdoor saltwater pool and 30 to 50 ppm for a chlorine pool. If your salt pool reads 120 ppm, it is high even for a salt pool. See our saltwater vs chlorine guide.

Does Marina drain pools?

Marina Pool Services does not list draining or refilling as a service. Its weekly service covers water balance, including chlorine, pH, alkalinity, calcium hardness, conditioner level and salt if applicable. A weekly test catches rising CYA early, before it climbs past 100 ppm. See the pool maintenance services page and the weekly service page.

For a Keller or Euless pool, see the Keller service area page and the Euless page. For general chemistry, see the water chemistry chart and the North Texas pool care guide.

When should I call a pro?

Call when:

• CYA reads above 100 ppm and the water is cloudy or green.
• You are unsure of your city’s current stage.
• The pool has algae and you cannot raise chlorine enough.
• You want a plan to bring CYA down in steps.

What should I ask my city?

Rules change with the stage, and a web page can lag. A short call or email can settle it. Ask these questions.

1. What drought stage is in effect today?
2. Does the stage limit draining and refilling a pool?
3. Is a partial drain allowed, and in what amount?
4. May I top off an existing pool, and with what method?
5. Where may I send pool water? Many cities limit discharge to the storm sewer or a creek, so ask before you drain.

Write down the answer and the date. Then plan the dilution in steps instead of one large drain.

Next step

If your pool chemistry is off and draining is not an option, see the weekly pool service page, then call Marina Pool Services at (817) 896-1120 or use the quote form at /contact.