Why is PH important in a Hot Tub | ehottubsandpools

Why is PH important in a Hot Tub

PH level in a hot tub is more important than you might think. I’ve come across many customers over the years that don’t ever test their PH level. They feel that if the water is clear, that’s all that matters. They add chlorine or bromine weekly and as long as the water looks good they don’t test anything else. I am going to give a few examples that will show why this is not a good practice to get into.

PH is measured in a range from 0-14. This is the same PH scale you learned in science class in school. 0 is the low end of the scale and in water is extremely corrosive. 14 is the high end of the scale and considered alkaline. 7 on this scale is the middle and considered neutral. The safest range to keep your hot tubs water in would be from 7.4 to 7.8. If the water in your tub falls out of this range to the low side, the water will become acidic and corrosive. This will not be good for your hot tub or your body. In the tub acidic water will corrode or etch any metal it comes in contact with. The heater in a hot tub is made of metal and won’t take long to corrode and stop working in acidic water. Now I’m not a doctor, but sitting in acid can’t be good for your body either.

If the water in your hot tub heads above the recommended range, it will also cause several problems. Some of these will be scale and cloudy water. Scale in hot tubs and swimming pools is caused by high PH which allows minerals in the water to fall out of suspension on to tub surfaces. This will leave behind a chalky or gritty residue on the tubs surface and inside the plumbing lines that will break down any plastic or rubber components in the hot tub. The other result is cloudy water. When the minerals in the water fall out of suspension they “show themselves” in the water.

Several factors can cause PH to change in the water. The two most popular reasons are fill water and the sanitizer being used. If you fill with hard water or well water, your PH will raise dramatically. Most well water I have tested comes out of the ground at a PH level of 8.6 or greater. This may differ in other parts of the country or world. The best way to know what is being added to your spa is to test the water coming out the fill hose. This will tell you whether you are going to change the PH level in your spa by adding fresh water. The sanitizer used in the tub will also affect the PH level. If you are using dichlor (stabilized granular chlorine) it has a PH factor of 6-7. This won’t change the level that much. Calcium hypochlorite (unstabilized granular chlorine) has a PH factor of 12-13. This will raise the PH level in your spa greatly. Bromine has a PH factor of 4-5 but less bromine is used in hot water than chlorine. Also remember that chlorine is not an effective sanitizer in water that has high PH.

Just because a hot tub looks clean and has clear water don’t assume everything in the water is fine. A hot tub with water in it that measures at a 6.0 PH level will be crystal clear. The reason being, nothing can grow in acid. The heater and other hot tub equipment will begin to corrode away and your eyes and skin will burn, but that water will look great. Do yourself a favor and test your spa water weekly for sanitizer and PH. It will save you time, money, and possibly your health. If you don’t have a proper test kit, get one. “Drop” test kits are more accurate than test strips. You can also take a water sample to a qualified pool or spa professional for testing. They will be able to tell you what is in your water and how to adjust it. But be careful don’t get over sold by a salesperson.

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3 Comments

  1. go to your local hardware store in the paint section and get some muriatic acid. pour this on the inside of the empty tub. it will wash off the scale as quick as you pour it on. Make sure you have a hose running in the tub to neutralize the acid. then read “protect your your hot tub from stains and scale” on EHOTTUBSANDPOOLS. this will tell you how to prevent this from happening again. good luck.

  2. So I had my water professionally tested to know my PH level and it came in exactly where it needs to be but my alkalinity is high. So I tried to lower my PH and I keep getting the “grit” in the hot tub. I have used the exact amount of PH down and waited the appropriate three hours before retesting. Any suggestions on what would be the cause? I have drained and cleaned both the tub and filters now three times in the last two months due to this issue. I have even used the cleaner that is supposed to flush out the jets and pipes. No luck. Still have the grit, sometimes a residue on the sides of the tub. Yuk!

    • “protect your hot tub from stains and scale” is the post that will help you most on this site. Using a product called Protect Plus made by GLB will solve your “grit” problem. if you add the correct dosage of this product WEEKLY, this will solve your problem. the residue on the sides of the tub is either from your sanitizer being to low or your filter is to dirty. most important thing i can tell you about you hot tubs filter is to clean it weekly if the tub is used 3 days a week or more, or every 2 weeks if used 2 days a week or less. this will keep your water cleaner and make your filter last longer. if you check and fix these things, your hot tub should be cleaner and easier to manage. good luck.

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