How To Lower Ph In Garden

Download Article

When the water in a hot tub becomes too alkaline, its pH increases, and the condition of the water deteriorates significantly. The total alkalinity of the water will probably be high at this point, as well. To lower the pH in a hot tub, you need to add a pool acid capable of dropping both the pH and total alkalinity.

1
Understand the relationship between pH and total alkalinity. The pH of the water is essentially a measure of the level of acidity in the water. Total alkalinity is a measure of the water's ability to buffer and resist changes to the pH.^[1]
- More precisely, pH is a measure of the concentration of hydrogen ions in the water. Fewer hydrogen ions will cause the pH to spike.
- Total alkalinity's ability to measure the water's resistance is more accurately described as a measurement of "buffering capacity."
- When the alkalinity of the water becomes high or low, the pH will follow shortly after.
- Since the two are so closely connected, you will often need to correct both at the same time.
2
Know the signs of high alkalinity and high pH. You can usually tell when the pH and alkalinity of your hot tub are high based on the way it runs.^[2]
- When the alkalinity and pH get too high, chlorine-based disinfectants are less effective. As a result, the water quality deteriorates, causing build-up and other problems in the hot tub.
- Signs of high alkalinity include the formation of scales along the sides and bottom of the tub, cloudy water, skin irritation, eye irritation, and poor sanitary conditions.
- Similarly, signs of high pH also include poor sanitary conditions, cloudy water, the formation of scales, skin irritation, and eye irritation. The lifespan of the hot tub's filter will also decrease.
- Note that if you see corrosion, etched plaster, or stained plaster, the pH and alkalinity are probably too low. Rapid changes in he pH are often symptomatic of low alkalinity, as well.
Advertisement
3
Test the total alkalinity of the hot tub. Even if you suspect that the alkalinity of your hot tub water is high, you should confirm your suspicions by testing the water with an alkalinity testing strip or kit.^[3]
- An ideal range for alkalinity is between 80 and 120 ppm.
- Total alkalinity should be tested before the pH.
4
Test the pH of the hot tub. Similarly, even if you suspect that the pH of the water is high, you should take a precise measurement of the actual pH by testing the water with a pH testing kit or testing strips.^[4]
- The ideal pH range for hot tub water is between 7.4 and 7.6, but the acceptable range is between 7.2 and 7.8.
- If the water pH is higher than this ideal range, the water is too basic or alkaline.
Advertisement

1
Choose the right chemical. To lower both total alkalinity and pH, you will need to add an acid. Liquid muriatic acid (hydrochloric acid diluted to 20 percent) and dry sodium bisulfate are among the most popular choices.^[5]
- The acid combines with the water, thereby increasing the concentration of hydrogen ions and lowering the pH.
- Similarly, the acid reacts with bicarbonates in the water and reduces the water's total alkalinity in the process.
- You could also look for a generic "pH decreaser," "alkalinity decreaser," or "combination decreaser" chemical at a pool supply store.
2
Determine your initial measurements based on total alkalinity. The pH will drop faster than the alkalinity, so you need to fix the alkalinity first. Once you balance the alkalinity, the pH will gradually adjust to it.^[6]
- Always follow the instructions on your pH/alkalinity chemical when preparing the correct amount.
- As a general rule, you will need 1.6 lbs (725.75 g) sodium bisulfate or 1.3 qt (1.23 L) muriatic acid for every 10,000 gallons (37.85 kL) of water to drop the total alkalinity by 10 ppm.
3
Mix the chemical together with a small amount of water. Scoop water out of your hot tub into an 8 gal (30.28 L) plastic bucket until that container is three-quarters full. Pour the full amount of pH decreaser into the water in the bucket and let it dissolve.^[7]
- You must add the acid to the water. Pouring the acid into the bucket first and adding the water can cause damage to the bucket and may result in ineffective mixing.
4
Turn the hot tub on. Make sure that the pump and filters are running. The hot tub should be set at its usual temperature and speed before you continue.^[8]
- It is crucial, however, that no one is in the hot tub while you are balancing the water.
5
Add the diluted chemical to the hot tub. Slowly pour the diluted decreaser into the center of the hot tub.^[9]
- Pour the acid in gradually instead of dumping it in all at once. Adding the acid too quickly can cause damage to the sides, bottom, and equipment in the hot tub.
6
Give the water a chance to balance. Allow the pump to circulate the water for three to six hours after you add the decreaser.^[10]
- During this time, the pumps should circulate the water and acid together more thoroughly. Only after the two have been well combined will the pH and alkalinity be consistent throughout the hot tub, and you need to wait until these measurements are consistent before moving on any further.
7
Test the alkalinity and pH again. Test the alkalinity first, then the pH.
- If done correctly, the alkalinity should already be balanced. The pH may not be balanced yet, however.
- If either the alkalinity or pH is still high, repeat the process. Continue as needed until the water is well balanced.
8
Periodically drain the water. You should completely drain the water in your hot tub at least once every four to six months. Afterward, fill the hot tub back up, balance the pH and alkalinity as needed, and continue to monitor the conditions as usual.^[11]
- You will need to balance the pH and alkalinity of your water nearly every week if you use the hot tub regularly. Adding chemicals to the water so often can cause excess build-up, and you will likely notice that it is becoming more difficult to balance your water conditions.
- Once you notice this difficulty, it is time for you to change the old water out for fresh water.
Advertisement

Add New Question

Question

My pH is orange, does this mean it is high or low?

Konner Wilson

Community Answer

Your pH is low. This is slightly acidic, probably a 3-4 on the scale. Remember, green is neutral.
Question

Our hot tub's pH is too high, but the alkalinity is normal. We're using a pH decreasing product, but it still won't go down. How can we fix this?

Take a sample into your local pool retailer and have it analyzed. If your pH is high and adding pH decreaser has no effect, you could have what is known as pH lock. Have your source water analyzed to determine initial levels.
Question

Can itchy skin with a rash be caused by a pH imbalance in our spa?

The short answer is yes. The pH level can irritate your skin. The warm water will dilate your pores and the water will also rinse away any protective natural oils. If the condition is paired with a low sanitizer level, it creates an ideal path for bacteria to enter your skin and cause an infection.
Question

What can a high pH in a hot tub cause?

High pH can cause minerals to come out of the water and form scaling on your spa surfaces and equipment.
Question

Does it make a difference whether I have soft or hard water in my hot tub?

Yes, it does. You need some level of hardness in your water, particularly calcium. Most spa manufacturers and water chemists recommend somewhere between 150 - 300 ppm. When refilling or starting your spa, err on the low side and see how it goes. You need to have good balance between pH, total alkalinity (TA), and calcium hardness. Make sure you understand what you have in your incoming fill water before adjusting any of these parameters in your hot tub. Also, I highly recommend using liquid reagents as opposed to the more common dip strips for accuracy.
Question

If I put in a little too much acid, is it safe to use the spa?

Just to err on the side of caution, I would avoid using it until the acid levels are back to normal. Use the test strips designed specifically for the spa to determine when it should be safe enough to use it.
Question

How do I lower the hardness of my spa?

Drain your hot tub either fully or partially (depending on the calcium concentration) and then refill it. Do not add any calcium (hardness) increaser until you know what the level of hardness is in your incoming raw water. You need some level of calcium hardness (check with your manufacturer or google "spa water chemistry" to understand the appropriate level of calcium hardness requirement). Depending on your raw water you may have enough calcium hardness present so that you don't need to add any "calcium increaser" when you refill or top off your spa.
Question

I'm in the process of balancing my spa for the first time. I now have alkalinity in the acceptable range, but the pH is still too high. How do I decrease the pH without over correcting alkalinity?

Your pH should always be adjusted before adjusting the alkalinity. Alkalinity absorbs acids in the water. If you have a normal-to-high alkalinity and add pH decrease, it may be absorbed by the alkalinity before it can affect the pH.
Question

How do I fix too high alkalinity in my hot tub?

If the PH is normal, then turn on an aerator for a couple of hours and recheck. You will find the PH has increased and acid will need to be added to lower PH. This will in turn correct alkalinity. It may take several attempts.
Question

My pH level is fine but my alkaline is low. How do I rectify this?

It's more common to have high alkalinity than low alkalinity. Low alkalinity is usually caused by heavy rainfall (acid rain). Add sodium bicarbonate to the water to raise the alkalinity to 80ppm.

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Thanks for submitting a tip for review!

Wear gloves as you handle any pool acid. Never touch the acid with your hands or with any bare skin.
You should also consider wearing safety goggles. Otherwise, the acid may splash into your eyes when you add it to the hot tub.
Handle pool acid with extreme care. The acid can cause irritation, burns, and temporary/permanent blindness under the worst conditions.

Things You'll Need

pH tester
Total alkalinity tester
Large plastic bucket
Rubber gloves
Safety goggles
Pool, spa, and hot tub acid (muriatic acid, sodium bisulfite, or chemical decreaser product)

About This Article

Article SummaryX

To lower the pH in a hot tub, you can add liquid muriatic acid to the water to reduce the total alkalinity. Alternatively, you can use dry sodium bisulfate. Either acid will work. Whichever acid you decide to use, you'll need to dilute it with water first according to the directions on the packaging. Then, just turn on your hot tub, pour the mixture into the water, and let it circulate. When you're done, use a pH test kit to check the new pH levels in the water. To learn how to recognize high alkalinity and high pH in a hot tub, keep reading!

Did this summary help you?

Thanks to all authors for creating a page that has been read 273,218 times.