Fix a Leak Review: I Used It on My Own Hot Tub Skimmer Leak

Last updated: September 2026

I’d had a small leak in my hot tub for some time. Nothing drastic: a couple of centimetres (about an inch) of water a week that I’d been topping up. So I thought it was a good time to test “Fix a Leak” from Marlig Industries, a liquid leak sealer for pools and spas. I knew a couple of my customers had used it with success, so let’s see how I got on.

Below is what the product is, how it’s meant to be used, how I used it (not quite by the book), my results, and when I’d reach for it versus getting the spanners out.

What is Fix a Leak?

Fix a Leak is a blended, concentrated liquid designed to seal small leaks in pool and spa shells, liners and plumbing. You add it to the water, circulate it, and as water escapes through a leak, the material is carried into the hole, builds up and seals it. It’s rated to seal holes up to 1/8in (about 3mm) in diameter, and Leslie’s lists it as able to permanently seal leaks and holes up to 1/8in.

Sizes, dose and availability

	Details (September 2026)
Sizes	8oz (about 235ml) for spas and 32oz (about 950ml) for pools
Spa dose	Check your bottle. Current US listings give 8oz per 1,000 US gallons for minor leaks, with a second bottle for larger leaks, while others quote 4oz per 250 gallons (8oz per 500). Either way, one 8oz bottle covers most home hot tubs
Pool dose	32oz per 22,000 US gallons, according to current listings
Max hole size	1/8in (about 3mm)
USA	Sold by the big pool chains and online. Leslie’s lists the 8oz at $16.99 and the 32oz at $27.99
UK	FL-32 Fix a Leak 32fl oz at parts4tubs.co.uk

The maker also says it won’t harm salt chlorine generators, heaters, pumps or filters, though you still take cartridge filters out while you’re treating.

How you’re meant to use it

Shake well before using. These are the steps from the instructions, summarised.

Hot tubs and spas

1. Remove all cartridge filters before adding Fix a Leak to the water.
2. With the pump running, add it slowly through the skimmer or in front of another suction.
3. Keep it circulating for at least 4–6 hours a day, for up to 2 days, or until the leak has stopped.
4. It’s very heavy and settles to the lowest point quickly, so stir it back into suspension regularly while it circulates. Current instructions say every 4–6 hours.
5. Once the leak has stopped, give it 24–48 hours to cure before going back to normal filtration.
6. Put the cartridge back and run a normal cycle for 6–8 hours to collect any residue. Then take the cartridge out and rinse it under warm water straight away. You may need to rinse it twice.
7. Repeat the treatment if needed.

For foam-filled, shop-bought spas that have been leaking for a while, retailer instructions add that you should drain the tub afterwards and let it dry out for several days, so the foam around the leak isn’t left sodden.

Swimming pools

1. Bypass the filter media. On a sand filter, set the valve to recirculate. On cartridge or DE filters, remove the elements and circulate through the empty tank.
2. With the pump running, add it slowly through the skimmer or in front of another suction.
3. Switch the suction to the main drain. If you can’t, put the vacuum head in the deepest part of the pool on the normal vacuum connection.
4. Brush it back into suspension (or let an automatic cleaner do it) every 4–6 hours while it circulates.
5. Mark the water level and check it for 2–3 days to see if the leak has stopped.
6. After 24–48 hours of cure time, go back to normal filtration. Backwash a sand filter, or rinse cartridges and DE elements. Never let cartridges or DE elements dry out before they’re cleaned.

What about my leak?

What’s slightly different about my leak is that I knew exactly where it was: at the bottom of my skimmer, and I knew it was a bad joint.

I remember struggling with that joint when I built my hot tub. Afterwards I found I’d used the wrong adaptor, because I found the correct one still in the box. Doh! So I botched the joint, and guess what, it leaked. As I always say, joints not made correctly will eventually fail and leak. Here’s how to make a proper solvent weld joint so you don’t repeat my mistake.

When I did my control room remodel, I didn’t realise it was there. Otherwise I’d have cut it out (it’s encased in concrete) and remade the joint. My bad! If you know where the leak is and you can get to it, cut out the joint or pipe and remake it. That’s always the best option.

But I couldn’t get to it easily. Well, not really at all, as there’s now a load of plumbing in the way. So I gave this product a go.

My approach

The instructions have you circulate the product through the whole system, because the assumption is that you don’t know where the leak is. I did, so I focused on that area: the skimmer. My idea was that a concentrated dose right where it was needed might seal it up.

• First, I dropped the water to just below the skimmer, so water wasn’t coming in over the top of it.
• Then I closed the gate valve on the suction side of the pump. That gave me a “captive audience” of water in the skimmer and the pipe below it.
• My plan was to add the bottle to the skimmer in stages, stir every hour or so, and top up with water until it held, which would be easy to monitor.

This isn’t how the instructions say to do it. It worked for me because I knew exactly where my leak was. If you don’t, follow the instructions and circulate it.

Let’s get started

I killed the power to the tub, as I didn’t want the pumps to run for this. Instead I “circulated” it manually by stirring the water every hour or so throughout the day. With the gate valve closed, the water in the skimmer was isolated.

I added about a third of the bottle, and the water went cloudy very quickly. I topped up the water in the skimmer to a point where I could see what kind of loss we were looking at, and stirred to make sure it was well and truly mixed in. Then I left it for an hour or so before going back to stir again.

After a couple of hours

After going out to stir the water every hour or so, religiously, for about 4 hours, I decided to open the gate valve. There was no water loss in the skimmer, so I thought I needed a bit more pressure. I wanted to push more water, with the Fix a Leak in suspension, through the leak at the bottom of the skimmer, because the product works by binding to the hole and slowly blocking it up.

What I noticed straight away was that there were considerably fewer damp areas around the bottom of the skimmer. Could it be working already? At this point I was just over half a bottle in.

8 hours in

After 8 hours I decided it was time to fill up and get the heat back on. The ambient temperature was quite low and I didn’t want anything freezing up. Having done my little science experiment (watch the video on this page if you haven’t already), I knew it had probably cured in already, as I wasn’t circulating the water and was using a concentrated dose.

All filled up. Time to see how it held up over the next few days. There was already less visible dampness around the skimmer, so I was confident things were a lot better already. Pretty impressed, to be honest.

The next morning

The next morning I went to check the water level. I should have measured the exact depth with a ruler the night before, but I didn’t. Visibly, there was little to no movement from the mark I’d put on the tub.

However, there was still some water in the control room around the skimmer, so the leak wasn’t fully fixed yet. The bottle does say it takes time to cure. So I turned off the circulation again, poured the rest of the bottle into the skimmer, and waited to see how the second dose worked. With the water level at its normal height, I hoped the extra weight of water would push the solution into the areas that needed sealing.

24 hours on: the result

24 hours later I went back with a ruler. The level had dropped a couple of millimetres in 24 hours, which is not a lot at all, compared with the couple of centimetres a week I started with. I was pretty happy with that. The bottle says a second treatment might be needed, so I kept that in mind. But overall I was very pleased with the outcome. It’s a great product, and I’m sure plenty of DIYers like me will make use of it.

My verdict

Good	Not so good
Cheap compared with digging out a buried joint	Only for small leaks, up to 1/8in
Simple to use, with no tools	Needs stirring and babysitting for a day or two
Made a big difference to my skimmer leak	Makes the water cloudy while you’re treating, and the filter needs a good rinse afterwards
Can reach leaks you physically can’t get to	It’s a fix for a symptom. A badly made joint is still a badly made joint

When to use Fix a Leak, and when not to

Before you pour anything in, find out where the water’s going. Most leaks on a DIY tub are in the plumbing, not the shell, and many of them are easy to fix directly. My guide Hot tub leak? How to find and fix it takes you through the checks.

Good candidate for Fix a Leak	Fix it properly instead
A slow drip from a joint buried in concrete or foam	A dripping union: check the O-ring and hand-tighten it
A pinhole in a pipe or fitting you can’t reach	Water from the pump between the motor and wet end: a failed shaft seal, so replace it
Seepage around a skimmer or jet body that you can’t dig out	A split pipe or cracked fitting you can see
A small, steady loss you’ve confirmed isn’t evaporation	A structural crack in the shell, or a leak bigger than 1/8in

Evaporation catches a lot of people out, especially with the lid off in warm or windy weather. The classic bucket test (a bucket of tub water sitting on a step in the tub, with both levels marked) tells you whether you’re losing more than evaporation. If you’re building a tub now, there’s more on getting the skimmer right first time in how to install a skimmer. And for pump leaks, see should I repair or replace my hot tub pump?

Where to buy it, and building it right

In the UK, you’ll find Fix a Leak at parts4tubs.co.uk, along with replacement unions, O-rings and pump seals if your leak needs a proper repair. In the USA, try parts4tubs.com for parts.

And if you’re still planning your build, the best leak is the one you never have. My DIY hot tub plans include a full plumbing layout and parts list, so you’re not hunting for the right adaptor after the concrete’s gone in like I was. For the plumbing itself, see DIY hot tub plumbing.

FAQs

Does Fix a Leak work on hot tubs?

It can, for small leaks. It’s rated for holes up to 1/8in (about 3mm). On my own tub it took a skimmer leak from a couple of centimetres a week down to a couple of millimetres a day.

How much Fix a Leak do I need for a hot tub?

Follow your bottle. Current US listings give 8oz per 1,000 gallons for minor leaks, and some give 4oz per 250 gallons. One 8oz bottle covers most home hot tubs, and a second can be used for bigger leaks.

How long does Fix a Leak take to work?

Circulate it until the leak stops, which could take up to a couple of days, then allow 24–48 hours to cure before going back to normal filtration.

Will Fix a Leak clog my filter or jets?

Take cartridge filters out while you treat, and rinse them well afterwards. It’s heavy and settles quickly, which is why you need to stir it back into suspension. The maker says it won’t harm heaters, pumps, filters or salt chlorinators.

Is Fix a Leak a permanent fix?

It’s sold as a permanent seal, and it worked well for me. But if you can reach the leak, remaking the joint is always the better long-term fix.

Have you used Fix a Leak on your tub? Let me know how you got on in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi