What Causes Hot Tub Foam and How to Get Rid of It.

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Do you ever open your spa cover and find the tub full of foamy water? This is a common hot tub problem and leaves many people wondering, what causes hot tub foam?

Below, I’ll explain the causes of hot tub foam and how to easily fix this problem for good!

FoamTub

There are three main causes of hot tub foam:

Beauty Products

Believe it or not, foamy water can be caused by soap residue in your swim suit, as well as fabric softener, body lotion, hair products, skin oil and makeup.

Using a scum digester, such as Scum Buster will remedy foamy water caused by soap residues and beauty products. You can also help prevent hot tub foam by using your oxidizing shock after each use and a floating oil absorber, such as a Zorbo.

Low Calcium Hardness

Low calcium levels (aside from being damaging to equipment) can also decrease the surface tension in the water and allow for excessive sudsing.

To prevent this issue, use Hardness test strips once a week to check and maintain the calcium hardness level in your hot tub.  If low, use Calcium Hardness Increaser.

High or Low pH

Imbalanced water can cause all sorts of issues, from green, to stinky, to even foamy hot tub water.

Prevent foam due to high pH by using pH Decreaser. Use Easy pH for raising low pH. Test your water once per week (once every two weeks if using CWB) to maintain a healthy hot tub.

Based on the cause of your hot tub foam, here are some helpful products:

· Oxidizing Shock

· Easy pH

· pH Decreaser

· Scum Buster

· Zorbo Oil Absorber

· Test Strips

Have questions about water chemistry? Post a comment below and our hot tub experts will answer!

24 comments

  1. I really want to get a hot tub for my backyard. I think that it would be fun to sit in during the summer. I know that my wife would love one as well. I have never purchased a hot tub before, so I am going to make sure to do a lot of research before buying one. I can’t wait until I have a hot tub in my backyard.

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  2. Last night, I went to get into my hot tub, and I found something very similar to this. It wasn’t this extreme, but it was pretty bad. There was about an inch of foam. I had never had that issue before, so I can’t figure out what it was. I had no idea that make up, and other beauty products would cause foam like this.

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  3. Hi Lacey,
    Thank you for posting.
    Yeah, hot tub foam can suddenly occur and be quite a surprise when you go to get in.
    Have you tested your pH, alkalinity and hardness yet?
    Thanks,
    Kaisa
    The Spa Depot

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  4. Can we add kids to the list? I had my nephews pouring bubble bath in my hot tub because they thought it would be fun. What a mess! lol

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  5. Hi Joe,
    Thanks for posting. White flakes are usually caused by calcium build-up in the plumbing. Buildup in your spa plumbing can also lead to a host of problems such as hot tub foam and cloudy water.
    I recommend using a Spa System Flush: http://www.spadepot.com/shop/Spa-System-Flush-16-oz-P436C57.aspx
    To prevent this from happening in the future, be sure to test and balance your pH, Alkalinity and hardness level once a week.
    I hope this helps. Please let me know if you have any additional questions.
    Thank you,
    Kaisa
    SpaDepot.com

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  6. My hot tub is cloudy ,using clean water blue system chemicals,ph and alk are in req balance range and copper showing grey on test strips and shock after each use as called out. any solutions.

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  7. Hi Carl,
    I’m happy to help. To determine the cause, I just have a few questions:
    How old is the water?
    How old is the hot tub filter?
    Are you using Oxy Spa routinely?
    Please let me know.
    Thank you,
    Kaisa
    SpaDepot.com

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  8. My gym jacuzzi always has foam which I can smell urine. How can I make them correct this without getting banned from membership?

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  9. Hi Avis,
    Thanks for your post. You could try sending an anonymous letter explaining your concerns. I would strongly recommend not using this hot tub. An under-sanitized public hot tub can lead to serious illness.
    If the gym does not take immediate corrective action, I would contact your state health department with your concerns.
    Please let me know if you have any additional questions.
    Thank you,
    Kaisa
    SpaDepot.com

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  10. I will definitely try these products you’ve listed. Didn’t have slightest clue that beauty products could cause foam. Thanks for your insights!

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  11. My hot tub foams up and has bright kinda aqua green in it. It will leave a bright green scum around the hot tub. It only does this when we use the jets with air going through them. We have a Clearwater Belize spa.

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  12. Hi David,

    Have you flushed your plumbing recently? We recommend using Spa System Flush (http://www.spadepot.com/shop/Spa-System-Flush-16-oz-P436C57.aspx) to super-clean the inside of your hot tub plumbing. It will flush grime, oily residue and heater scale deposits that may be hiding, even if your jetted tub is well maintained.

    To use: remove filter, add half a bottle (8 oz.), run pumps and jets for a few minutes (or overnight if possible) then drain away the gunk with the old water. And that’s it!

    Thanks,
    Rosy
    SpaDepot.com

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  13. I am using a Nature Stick and a Cense oxygen infused aromatherapy crystals for my hot tub. Is that enough, or do I need to use more stuff?

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  14. Hi Doreen,

    Great question! Nature 2 and using an MPS shock (like the Cense product) after each use is pretty good at keeping the spa clean. You’ll still need to use pH adjusting products occasionally, of course.

    However, shocking with dichlor chlorine on initial fill and when occasional problems arise is a good idea. Many people use a small dose of dichlor in their weekly routine to avoid cloudy water. Chlorine doesn’t stick around in the water too long, so you don’t need to worry about soaking in chemicals.

    Thanks,
    Sarah
    SpaDepot.com

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  15. Hi. We drained, vacuumed out the jet ports and completely washed our hot tub yesterday. Friday afternoon, I put a drain prep in the water to clean the plumbing. After filling with oir local water supply, our alkalinity is 350ppm, pH is 8.2+ and zero bromine. I added 200ml liquid acid, 70 gm bromine booster, 120 gm shock and 26ml clarifier. I tested and added an additional 200ml acid late last night after a retest showed the alkalinity at 290ppm. This morning the readings are alkalinity at 230ppm, bromine 1.0 and pH at 8.2+ and we have foam on the water when the pumps are started. I added another 300 ml liquid acid this morning. But what I am struggling with is the foam. Why is this fresh water foaming so much?

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  16. Hi Ed,

    Thank you for your question and I really appreciate the details you have provided! The only thing I don’t see in there is calcium (hardness), have you tested the water’s hardness?

    Thanks,
    Sarah
    SpaDepot.com

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  17. Yes, I forgot that detail. Hardness was tested at 250 ppm. And I should also mention we use liquid reagents, not test strips or digital meters.

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  18. Hi Ed,

    That’s great to hear that your hardness is in balance, that means you don’t have a more difficult issue on your hands. The foaming is most likely caused by the extremely alkaline water reacting with the acid you are adding, not unlike a baking soda volcano from grade school science class.

    Keep adding acid at 12 hr intervals, like you have been doing. Sometimes it takes a surprising amount of acid to bring the pH down. If the acid you are using is a pH Decreaser Liquid type product, then it may even take a few bottles. A buffered muriatic acid like Acid Magic could help you in the future with bringing the pH down significantly.

    As for the Total Alkalinity, you can lower that by turning on your jets! Aeration is a great way to get TA down once your pH is in balance.

    Let me know if there are any issues or you have any questions.

    Thanks,
    Sarah
    SpaDepot.com

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  19. Hi Sarah. Thanks for your replies. The acid we use is a buffered muriatic acid named Acid Enhance purchased from a hot tub store in my area. This is the 2nd fill we’ve used it with but the last one didn’t foam like it did this time. However, the alkalinity in our water started at 240 ppm, also unlike this time at 350. Since my original post, we added another 150 ml acid and this morning had respectable numbers at 80 alkalinity, 3.5 bromine and 7.6 pH. I will now turn the air OFF to the jets in hopes of keeping it balanced for a period of time. I haven’t run the pumps yet to see if the foam has subsided, bit I will let you know when I check that.

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  20. Hi Sarah. The water has been nicely balanced since Monday. The alkalinity is 60, pH at 7.6 and bromine at 3.5. We’ve always had an issue with lower alkalinity readings when the pH is in a good range, so this is good for us. We use the Langlier Index to ensure oure water quality. However, that pure white foam is still forming on the water when the jets are started. Any rhoughts?

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