JoyfulNoise said: The CYA is not going to affect bromine. Theoretically, high CYA levels could slow down the conversion of bromide into bromine because the CYA would make the hypochlorous acid (HOCl) levels a lot lower, but that would be really hard to see....and you'd need very high levels of CYA.
Note: Since cyanuric acid stabilizer doesn't work with bromine, there is no need for a CYA test in kits that only contain a bromine sanitizer test, such as Taylor's Complete™ FAS-DPD kit (K-2106).
Unfortunately, there is no known stabilizer for bromine that even approaches the effectiveness of cyanuric acid on chlorine, so it is best used in covered and indoor spas.
Our bromine tablets are a mixture of 61% bromine, and 27% chlorine, but require no stabilization. However, it is generally accepted that when using bromine, one should increase the residual by a factor of two, or double the dose. This may lead you to think that you would use double the amount of bromine tablets.
Cyanuric acid is raised by adding chlorine stabilizer containing cyanuric acid. The only way to lower cyanuric acid is by replacing water.
2. Dichloroisocyanuric Acid: Also known as “dichlor,” this is another type of chlorine shock. Dichlor contains both chlorine and cyanuric acid and will, over time, raise your cyanuric acid levels.
The problem with low cyanuric acid is chlorine degrades quickly in the presence of sunlight. Chlorine is rendered completely ineffective within a few hours of sun exposure. If you didn't have cyanuric acid in your pool or it was low, you'll find that you need to add a lot more chlorine to have effective sanitization.
Direct sunlight received by your pool
Without any stabilizer, the sun can destroy up to 90% of the chlorine in two hours. The energy contained in UV light from the sun causes the hypochlorous acid and hypochlorite ions formed from the reaction of chlorine and water to break apart in a process called photolysis.
Does Bromine affect pH level? Bromine has a low pH of around 4, and using bromine tablets will slowly lower pH and alkalinity over time, requiring additions of a base chemical to raise pH and alkalinity. The same can be said for chlorine tablets, which have a pH even lower, around 3.
If you have one of the better designed floating dispensers like this one, it's safe to add up to 6 1-inch tablets at a time. If your dispenser looks like this, or you're just adding the tablets to your water without a floater, I'd recommend starting with just 1-2 tablets.
Cyanuric acid and stabilized chlorine (dichlor or trichlor) may be used in outdoor swimming pools only. It must not be used in indoor swimming pools, therapy pools, spas and hot tubs, or in pools using a bromine sanitizer. Cyanuric acid levels must never exceed 90 ppm.
When they are too high in a hot tub this can be uncomfortable for hot tub owners to sit in. High bromine/chlorine levels can be very irritating on a person's skin, eyes and respiratory system. It can cause red itchy skin, red itchy eyes, and effect the lungs in a negative way.
If you have a spa, bromine has a lot of advantages over using chlorine. It may cost a little bit more, but it lasts longer and does a much better job than chlorine at killing bacteria, especially at high temperatures and high pH levels.
You will have to drain as adding chlorine to your current tub will just convert the bromide back to bromine. The bromide will dissipate eventually but take an extremely long time to do so, so a water change now is the only way to quickly convert from bromine to chlorine.
CYA will help you keep a better chlorine reading in your pool. Just be careful how much extra cyanuric acid you add to your water. It's very hard to lower your CYA levels if they're too high. And cyanuric acid does not evaporate or break down like chlorine, so it will linger in your pool water.
If you are sanitizing your spa with bromine, you should shock your spa with Spa Selections Non-Chlorine Shock Oxidizer on a regular basis to oxidize the waste out of the water and reduce foaming. Spa Selections Bromine is a two-part system, including Spa Selections Brominating Tablets and Spa Selections Brom-Start.
Use fresh, high quality test strips. Excessively high bromine or chlorine levels can result in false pH and TA readings.
Other factors can be the water you've used to fill up the tub, or any chemicals you've added to the water. If the water source is acidic to begin with, your pH will test low, and acidic chemicals like chlorine and bromine can also drop the pH.
Chlorine works faster to kill contaminants but for a shorter period of time, as it dissipates faster. Bromine kills contaminants more slowly but for a longer period of time; plus, it can help keep water chemistry more balanced due to its low pH, meaning less chemical adjusting is needed.
Partially drain your spa and refill with new water. For diluting, you don't have to use an exact science, but basically, if your cyanuric acid level is 5% too high, then you need to remove about 5% of the spa water and replace with fresh water.
CYA Buildup is Real
This means that for each 10 ppm of chlorine added to the water from dichlor, the CYA increase is 9 ppm. In other words, a 300-gallon hot tub adding 1 1/2 teaspoons of dichlor four times a week can build up a CYA level of 50 ppm in as few as four weeks and reach 100 ppm CYA in only seven weeks.
Does Muriatic Acid Affect Cyanuric Acid? Both muriatic acid and cyanuric acid can be used in your pool with minimal adverse effects on each other. Although, as with any chemical, it's best not to dump a whole lot into your pool at the one time or mix chemicals.
Why You Have Low Cyanuric Acid
The most likely reason is that you've only ever used unstabilized chlorine in your pool. Heads up: Unstabilized chlorine, such as sodium hypochlorite (liquid chlorine), lithium hypochlorite, and calcium hypochlorite, is pure chlorine.
Answer: Cyanuric acid shouldn't be at Zero for an outdoor swimming pool because chlorine will deplete faster in hot and humid weather, leading to cloudy water. If your FC is at normal level of 3ppm, raise Cyanuric acid level to 40 ppm and you will reduce chloramine levels that make your water appear cloudy.
As mentioned earlier, it will take at least 48 hours and up to a week to fully dissolve. Powdered cyanuric acid is not so common and it may not be available to buy in your area. It's reported to not dissolve any faster than granular stabilizer.