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Fix-a-Leak for Hot Tubs: a Guide on How to Properly Use a Leak Sealer

Sealants work in about 80% of cases, and they are cheap enough to be worth a shot

It’s not uncommon for water spas and hot tubs to spring a leak. When that happens, you’re often in for expensive repairs and considerable hassle. Leak Sealer is a much easier and cheaper solution.

Most hot tub owners already know about leakage sealants, but there are still many questions about these products in online stores.  In this article, I’ll explain what a sealant is, how effective it is and, most importantly, I’ll give you a step-by-step guide on how to use it properly.

A Brief Guide To Sealants

Put simply, a sealant is a concentrated liquid that plugs leaks in spa/hot tubs/pools.

Using sealant helps you avoid expensive repairs.  It can be used for materials of all kinds. Sealant does not damage the hot tub or spa’s pumps, heaters, filters, chlorine salt generators or other equipment.

The sealant is mixed with water. When the water begins to seep from the leakage source, the sealant forms a coating on the outside. When this dries, it forms a long-lasting seal. 

What kind of leakage can be stopped by sealant? 

Sealant won’t fix everything, but it’s a great solution for small leaks.  

Suitable applications:

  • For all types of spas, hot tubs, and pools.
  • For leaks in walls, floor, housing, return lines, suction lines, skimmers, fittings, etc.
  • For water loss in spa / hot tubs of less than 3 mm per day.
  • For water loss in pools of less than 5 cm or 50 mm of water per day.
  • For hot tubs with a salt level up to 3000 ppm.

Unsuitable applications:

  • For anything with fish or other living things.
  • For water loss in spa / hot tubs of over 3 mm per day

If you’re not sure that the sealant will eliminate all your leaks, I still recommend trying it first, since this easy-to-use product can save you more complex and expensive repairs.


Our team reviewed each of the 12 available sealants and ranked them by their efficiency and safety of the chemicals. The most effective products are Marlig Leak Sealer and Spa Choice Seal a Leak. What about the rest? When tried in the lab, it turned out that 8 of the 12 products didn’t work at all.

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How to use a leak sealer – step by step instructions

It’s very important to follow these specific steps to fix a leak, as otherwise you might get no result or even damage your hot tub. 

Step 1. Identify and fix water loss within 24 hours

You don’t need to know the source of the leak.

You just need to fill the spa and fix the water level (with scotch tape/marker or something else). After 24 hours, check and fix the new water level. Leave marks until the end of the repair.  This will help you monitor the results.

Step 2. Calculate the amount of the sealant required 

Hot tubs use a 4 oz (120 ml) for each 250 gallons (950 liters) of water.

 So on average:

  •  a hot tub for 2 people (200 gallons) requires 3.2 oz
  •  a hot tub for 4 people (300 gallons) requires 4.8 ounces
  •  a hot tub for 6 people (350 gallons) requires 5.6 ounces

(We use average volumes of hot tubs. Your hot tub may vary).

Also, note that it may be necessary to re-apply the sealant and possibly increase the amount. So it’s best you purchase the larger sealant bottle.

Step 3. Remove all cartridges or filtering devices

You need to remove the filters to prevent them from sealing. Continue to circulate the water through the empty filter tank.  

Step 4. Turn on the pump

The concentrate should be added directly to the water.

Although the seal will work regardless of the water temperature, for best results the temperature should not be below 70 ° F. From my observations, the seal works best at water temperatures above 100 ° F.

Step 5. Shake the sealer and slowly add to the water

Before use, shake the suspension vigorously.  Then slowly add the seal through the skimmer or any suction port.

Step 6. Recirculate water for 6-8 hours

The seal is very heavy, so it sinks to the bottom.  So, in addition to pump recirculation, you can help the sealant rise from the bottom by stirring (sweeping) it with a soft broom.

Recirculate and clean the hot tub floor until the leak stops. Turn off the system.

Step 7. Check the water level the next day

Check carefully for water loss.  Make the new measurements and compare the results. Your leakage will have either stopped completely, partially or not at all.

  • If the hot tub has ceased to leak, go to Step 8
  • If the leak has slowed, but not stopped completely, repeat the treatment (all previous 6 steps).
  • If the leak does not stop, you can increase the product quantity and try again.  But if the leak doesn’t stop after several attempts, it’s probably too large or in a place that the sealant can’t reach.  In that case, contact the professionals.

Step 8. Do not restore normal water circulation for 2 to 4 days

The sealant must dry and solidify to form a strong long-lasting seal.

Step 9. Reinstall the filter and clean the cartridges for several days

You do not need to drain the water. The sealant does not affect the chemistry of the water, and excess product will be eliminated with the restoration of normal filtration.

Reinstall the filter and resume filtering.  Note that the filter cartridge used to remove excess sealant must be cleaned several times until the sealant is completely removed.  Do not allow the cartridge to dry until it is thoroughly cleaned.

Step 10. You can enjoy your hot tub again

Bathing can resume after the filter has been used to remove the excess sealant and the chemistry is optimized.

Depending on the size of the leak, it might take several tries to seal it.  But when the leak is sealed, it’s usually a permanent fix.

However, leaks in pipe cracks or volumetric joints may be subject to vibration or pressure expansion and so might not be permanently sealed.  And some leaks, because of their location, size or water loss, may need repairs by a qualified technician. 

But fixing leaks with a seal is definitely worth trying. This method takes little effort and money and can be an effective solution.

Leak a seal reviews

Most of the reviews are positive, although there are people who used the sealant in a wrong way or just the crack was too big for this type of sealant. You can find some reviews below:

It worked like magic! Following the bottle directions, the leak stopped! That was ½ the bottle. When getting up standing water under the tub body I bumped some lower lines and sprang a leak that must have been sealed. Then I used the other ½ of the bottle with the same process and it is holding! … again! Possibly even better than the 1st? Time will tell.

– Donald Grabowski (Marietta, US)

Hopeful. I used 1/2 bottle and the leak stopped. After waiting for 24 hrs, I drained the hot tub, cleaned, and refilled. The leak came back. After research online, I concluded that I didn’t wait long enough for the stuff to set up properly. This past weekend, I put the remainder of the stop leak in and the leak has stopped again, I think. This time, I’m going to wait about five days before I clean and refill. Hopefully, this will do it. Instructions should be much more explicit on proper use!

– Terry Watkins (Plymouth, US)

Spa leak. We use about 10 ounces once and we still waiting to see water on the side of the jacuzzi, it has been dry, not a drop, we think it’s fixed. we still can’t believe far so good!

– Susana daveris (Vacaville, US)

How to prevent leaks in the future

The elimination of leakages when they first start, along with some preventative measures,  greatly increase the chances of a simple and successful repair. You should take the following precautions:

  • Keep a regular eye on water leaks
    Whenever you change the water, open the cabinet and look at all connections, checking whether they are dry.
  • Pay close attention to the pump
    Check the pump for signs of water (water spots or rust).
  • Keep the water properly balanced and clean
    Low pH and high bromine/chlorine content can cause leakage over time.
    You can use strips or digital meters to check the pH of the water.
  • Minimize the amount of vibration.
    You can minimize the amount of vibration by placing your hot tub on thick rubber


Leak sealer products can save you stress, time and money. Sealants work in about 80% of cases, and they are cheap enough to be worth a shot. If you have a leak that you can’t detect, sealants are your best choice. Only for bigger leaks and cracks are you likely to need professional help.

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