Building a DIY Stock Tank Pool

Occasionally, we take a break from drinking whiskey long enough to build and/or fix things here on Thirty One Whiskey. And last summer, we did just that – we built a stock tank pool. And then we spent the rest of the summer fixing what we’d built. And we learned a lot in the process.

Stock tank pools have seen a huge increase in popularity, and for good reason. They are significantly cheaper than a normal pool, look way better than an inflatable pool, and can be highly customized to suit each owner. And with the ongoing lockdowns and social distancing due to the COVID-19 pandemic, last summer was all about investing in making your own backyard a small oasis.

We borrowed knowledge from the multitude of helpful articles and lessons learned from other online bloggers, but we still ran into a few roadblocks and dilemmas to solve along the way — so here’s our own contribution of lessons learned building a DIY stock tank pool: the good, the bad, and the ugly.


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Parts List

For those looking for a TL;DR, here’s my parts list:

The (Original) Plan

In theory, this can be pretty straightforward and simple. A stock tank is simply a large galvanized steel tank that’s designed to be filled with water and left out in the elements, so theoretically you can just throw one in your yard, fill it with water, and be done with it. But it’s not going to look exceptionally ‘cute’ (wife’s words, not mine) and if you use chemicals to maintain the pool they may interact poorly with the steel. So, for us, some additional prep work was always going to be necessary.

The original plan for this pool still sounded pretty easy. Some of the Pinterest posts my wife sent me talk about simply grabbing a tank, spraying Flex Seal in the bottom, and calling it a day. I was down for that… but the problem comes when you dig a little deeper (i.e., read the comments sections). Those who had followed the Pinterest instructions talk about the rubberized Flex Seal peeling off within a year, needing to completely re-finish the tank afterwards. We attempted (attempted being key word here) to circumvent those issues with a pool paint; however, we also ran into issues with that tactic, as I’ll explain shortly.

The reason that the Flex Seal peels is the same reason that simply slapping some regular outdoor paint on this puppy and calling it a day won’t work: the galvanization process the metal is treated with makes it difficult for things to stick to the sides, which is good for keeping it rust free but bad for additional surface coatings. So if you plan on doing any sort of painting or sealing on the inside of the pool, you also need to prep the surface with a primer specifically designed for adhesion on galvanized steel.

There’s also the question of where to put the finished pool. Sure, you can just drop it on the ground — but you have to ensure level ground first. And then you have to consider the surrounding area / landscaping you want. My wife and I went through about four iterations for the design of the area around the pool ourselves before we came to the final design. First, we considered putting down a bunch of gravel but decided that gravel would be too difficult to remove if we ever wanted/ needed to; then we briefly considered a concrete patio but didn’t think we could complete the required drainage structures ourselves. We also considered making a solid wood deck to put the whole thing on but were concerned about the weight of the pool on it. In the end, we decided that the pool would sit on the (leveled) ground, and we would build a wooden deck that would fit snugly around it.

We also decided that there would need to be a pump to circulate the water and keep it filtered and clean, which required drilling a couple holes in the tub and buying the parts for the filter system. You don’t technically need this, but most stock tank owners seemed to vouch for this extra effort to keep the pool clean and prevent algae buildup or becoming a mosquito breeding ground.

Painting the Stock Tank

One thing we learned from reading other people’s experiences is the value of proper surface preparation. There’s usually some oil and residue on the surface of the galvanized metal that needs to be stripped away, and we found that using a little bit of vinegar is the ideal thing to do here. Not only will it get rid of that residue, but it should also slightly etch the surface, giving the paint a better chance of adhering to the surface.

This was pretty quick work and only took a few minutes, but you do need to wash out the stock tank completely after you’re done. (Side note: be aware that your lawn may turn temporarily brown where you washed out the vinegar, but it should bounce back in a couple weeks.)

While you’re in here, take a good look at the corners and the edges. Our stock tank looked like it was nicked by a forklift at some point and there was a small hole in the side. We were able to take a hammer and bend things back together (and the interior paint sealed it up from there), thankfully. But we learned lesson #1: don’t assume; make sure that you check for holes before you start filling the pool.

Even with the vinegar trick, this material can be difficult to paint. The galvanized steel means you need a specific kind of primer to go down on the metal before you apply the top coat of paint, but that primer does seem to be pretty readily available. I linked the one I used at the top of the article.

(Also, I made an amateur mistake here: I painted before drilling holes for the eventual filter/ pump that I would need to affix. See the section below on Pool Pump Installation & Maintenance for more information, but long story short: if you paint before drilling, you’ll find yourself cleaning tiny metal flakes out of your new pool paint. So if you plan to drill any holes for pumps, do so before any painting.)

I started with the interior, painting the bottom and sides of the pool as those would be the hardest to accomplish and the most annoying to access.

For me, the metal primer that I used for the metal (linked up top) was absolutely amazing. It adhered to the metal like a magnet to the Titanic, sticking solidly even despite being exposed to the pool water and such. Heck, it even stuck to the metal despite being power washed.

Why was I power washing my new stock tank pool, you ask? Well… lesson #2: don’t use rubber based pool paint on the interior.

Going back to our original research and planning, I remembered reading that Flex Seal on the bottom of the pool flakes off and doesn’t work for more than a month or so. Originally, I thought I was being smart by adding a layer of rubber based pool paint to the interior of the pool on top of the metal primer, using something actually designed for pools instead of something out of a can. Turns out that was the wrong call.

It took less than a month for the paint to start peeling off the sides. It started slowly, but then accelerated to the point where my wife was peeling entire sections of paint off the wall of the pool. Eventually, it got so bad that we resigned ourselves to emptying the pool, power washing off the pool paint, and adding a couple more layers of the primer. Given that this happens with Flex Seal as well as rubber-based pool paint, and that it seemed to only happen to areas where the pool water was in contact with the paint, my working theory is that the rubber and the metal were expanding and contracting at different rates which caused the paint to pull away from the wall.

It was impressive that the primer resisted the power washing, but learn from my mistakes. Either go bare metal, or just stick to the primer.

We also wanted to paint the exterior of the pool, which thankfully turned out to be much less eventful. The wife picked out a bright teal color for the pool, and it took a few coats with a paintbrush to truly achieve a smooth and even coat across the entire surface. But, beyond those extra coats, this has been possibly the least problematic part of the pool. That external paint never had any issues and still remains firmly affixed to the surface to this day (approximately 8-9 months, as of this publication date).

This entire painting process took two full days to complete. The longest part wasn’t the painting, but rather waiting between coats for it to dry.

Setting the Stock Tank

For some people, throwing a tank in the yard and filling it with water might be all the effort it takes. But for those who are wanting to make this a slightly more permanent fixture, a little effort preparing the location will go a long way.

The critical factor here is to make sure that the tank is evenly supported across the bottom. The sides and bottom of the stock tank aren’t all that thick, so any pressure points have the ability to eventually cause the metal to wear and break, which will lead to leaks and other bad stuff. Keeping it level is key.

Find the right spot in your yard, where you want this to reside permanently. Ideally, somewhere relatively level to save yourself some extra time and effort, but you can always make it relatively level, if needed. Add/remove soil as needed to level it out as best you can, making sure that you have enough soil to support the entire base of the pool. If you’re landscaping around it with gravel or sand, that should work to support the base too. Just be sure to continually check with your level and tamp down the surface well.

Once you’ve got it set up, put the pool down and double, triple check that it’s actually level with a spirit level. Sit in it, make sure that you like it where it is. (And, most importantly, have the wife sit in it and make sure she likes it).

Pool Pump Installation and Maintenance

While a pump isn’t technically necessary, it does a great job keeping the water nice and clean with minimal effort on your part. That said, even with the best laid plans (which I really thought I had), this was the component of the pool that had me about ready to file for divorce.

When I put this pool together, I painted the stock tank first, put it in place, and only then did I actually cut the holes for the pump fittings. Which was a mistake, of course: the metal chips from drilling the holes go everywhere, and there’s a chance that they might get stuck in the bottom pool paint, making for a dangerously sharp hazard to bare feet in your new pool.

Which brings us to lesson learned #3: drill the holes for the pool pump before you start painting. The drill bit I linked above takes some time to get the pilot hole through — but once it does, the sharp edges makes short work of getting a nice even and round hole in your pool.

Just make sure you thoroughly rinse all of those metal flakes and chips out of the pool before moving on!

In terms of location, I don’t think there’s necessarily a wrong choice here. Just make sure that wherever you place the openings, they will be completely underwater. I decided to place the intake suction port a little lower than the output port because I figured that would move the water a little more effectively.

On my tank, the seam where the two sides of the wall were connected seems to have made for a flatter surface than the rest of the stock tank, so I decided to drill close to that seam. But with the sufficient application of sealant, you shouldn’t need to worry too much about getting it completely flat.

Into those two holes, slide the pool pump fittings. The wall fittings I listed above should do the trick — all you need to do is slide them through the hole with the gasket seated on the inside of the pool flush against the stock tank wall.

And, for me, this is when the nightmare started in earnest.

I had read a bunch of articles about this process, and in some cases they recommended putting a bead of silicone caulk around the gasket on the inside of the pool. This made sense, since the pool wall isn’t flat and having a little extra filler seems to be a good idea. But it’s not a good idea. The silicone breaks down, and you’ll probably start to see some trickles of water around the rear of the pool.

For me, it all began with a slow leak in both of the fittings. I thought that I probably hadn’t clamped the backing down tight enough, so I gave it a couple more twists. But no, that didn’t work. The pattern on the metal surface was just strange enough that I couldn’t get a good seal, and water would continuously leak out from the side wall.

For one of the connections, adding a second gasket on the outside did the trick, so you may want to order a replacement gasket kit just in case and proactively fit the second piece of rubber on there to really and truly seal it up.

The catch here is that adding a second gasket means there isn’t enough room to put the aerator back on the fitting. In other words, you now have a rather large hole in your fitting. Another lesson from the other side: don’t just fill it with silicone caulk and call it a day — it’ll never dry. I eventually ended up using some Flex Tape and a metal hose clamp to apply pressure to the top of the opening and seal it shut, and that’s seemed to do the trick.

On the other fitting, the second gasket didn’t work. I even resorted to grabbing a metal punch and a hammer and bashing on the plastic nut so hard that some of the finger grips chipped off, but it still kept leaking. In this case, some Flex Shot caulk did the trick — I just backed off the nut, coated the whole thing in Flex Shot, and tightened it back down. Worked like a champ.

Lesson #4: just use Flex Shot to seal the pump from the start. The caulk probably disintegrated from being constantly underwater, whereas the Flex Shot is designed to live there permanently. As a result of this trial-and-error, the back of my stock tank doesn’t look quite as pretty as it used to… but at least it’s dry now. And it also took me a full week to solve all of those issues, which is just wasted time.

Final word of wisdom: don’t skimp on the hose clamps for the hose connections. It’s a critical part of the whole setup, as there’s too much pressure for them to stay in place on their own. The plastic ones may be OK depending on your setup, but metal hose clamps are also an option if you want something a little more secure.

With the pump properly installed and sealed, I ran an extension cable from the house to a waterproof box next to the pump. In the box, I connected the pump to the end of the extension cord and put the Kasa smart plug in between the two. This allowed me to control the pump from my Google Home, and even schedule it to turn on and off to conserve power and keep the pump from wearing out too quickly.


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Building the Deck

A lot of the actual pool construction went terribly wrong. But one thing that I think we actually did pretty well was the deck around the pool.

If you’re cool with stepping out directly onto the grass, or if you set up your pool on an existing concrete pad, you can probably skip building any additional structures around the pool. But it’s awfully nice to step out of the pool and have a nice clean surface to dry off on before you need to walk back into the house, not to mention it helps keep your pool cleaner since you don’t have as much debris on your feet when you step in.

For my design, I settled on a split structure. The front half is a nine foot long by eight foot wide section, with plenty of space for a deck chair to lay out on. The back half would only be five feet, but it would be raised to be level with the top of the pool — not only providing a nice spot to sit but also (thanks to a little extra work adding a flip-up section) making the perfect storage spot for the pool pump and miscellaneous pool accessories.

I briefly considered building a solid deck and resting the pool on top of the wood surface, but building something that could handle the weight of the water combined with up to four adult humans was too much of a challenge for me.

The tricky part here was fitting the pool inside the deck structure. Instead of just being a big square hole, I wanted to have a half circle cutout on each side that the pool would fit snugly inside. But, with a little planning, it was pretty easy.

My canine supervisor kept a close eye on the project.

First I laid out the deck as it would be once it was installed, but I only screwed in the support beams underneath to the edge boards. The others were just positioned on top. Once arranged, I took a three foot length of string, nailed one end to the middle board, and used a pencil on the other end to mark out where the pool would eventually rest. Then I used a ruler to mark out the straight cuts I would need to make to create a hole that size, and used a hand saw to cut them to shape.

Also, be sure to use pressure treated wood, as it’ll stand up better to the moisture from the pool and the weather.

Once you’ve got the boards for the deck cut out, it’s time to put it all together. With the stock tank pool in place and level, square up the frame of the deck, tack it in place with some screws, and start putting the boards back in the same order you had them in the mock up. For me it took about a solid day per side of the deck to get it fixed up.

Since this is going to be right next to a pool, it’s going to see a lot more moisture, water, and harmful chemicals than normal. So while I’d usually say that leaving it as bare wood would be fine, in this case you’re really going to want to put down a deck sealant of some sort. I used one that came combined with a cedar stain to match other wood features on the house, but clear is also an acceptable option.

Finishing Touches and Ongoing Maintenance

In my parts list, I mentioned some pool noodles, and they’re not for playing — they’re for the rim. The metal rim can get hot and can be uncomfortable, so adding some foam pool noodles will make sitting in your stock tank much more comfortable. Slice open one side of the pool noodle lengthwise, being careful not to cut the whole way through. Then slide the noodle onto the rim. It should have enough integrity to stay snugly on the rim without any adhesive or other tools.

For the chlorine, simply add a chlorine tablet to the chlorine dispenser and then put it in the water to float. I recommend closing the doors on the side of the dispenser, as you really don’t need that much chlorine added to the pool to work. Test the pool regularly and alter your chlorine addition as needed — leaving the pool uncovered will allow the chlorine to dissipate if you have too much.

Regularly check your filter in your pump, especially if you are using the pool a lot. The filter will eventually get clogged with crud, and the first indication that you need to change it will be when the output vent feels like it isn’t blowing water as forcefully as before. For me I think I get by with one filter every two weeks during the high-use summer, but your mileage may vary.

So there you have it: everything that worked (and more importantly, didn’t work) for me when I installed my stock tank pool in the summer of 2020. I did some things right, learned a lot more ways to do it wrong, and in the end had many afternoons and evenings spent enjoyably in that cool water.

Feel free to add your own successes and failures in the comments for others to learn from!


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17 comments

    1. Honestly the biggest takeaways for me are all about surface prep and paint selection. Get the right primer, and don’t use Flex Seal or pool paint on it or you (like me) will be power washing it within a couple months.

      But man oh man, especially here in Austin, this thing is worth its weight in gold during the summer.

      1. So did you do any other paint/sealer on the inside or just the primer? I’m getting ready to prep mine and this article was helpful about the sealing and drilling holes before painting.

  1. Been wanting to do this for years! I’ve seen some setups without a pump but I live in southeast Louisiana and don’t think that’s realistic to keep pool clean. Curious to know how often do you run the pump?

    1. Good question! We have ours hooked up to a smart plug, and we run it in an “every other hour” schedule. So on the even hours it runs, and on the odd hours it’s turned off. You can probably run it continuously, but we figured that’s the sweet spot for best filtration and least power use.

  2. Thanks for all the tips! Everything I bought off your list was perfect. Only one huge problem, the bottom seam is leaking underneath has anyone you know done flex seal to just that center seam with any luck?

    1. Oof! Like, the seam around the edge on the bottom? We had a similar issue where there was a puncture there, we hammered the hole closed, used some epoxy to seal it, and painted over it with the galvanized steel primer. So far that’s held for us.

      Running some of that flex seal rubberized tape on the outside would be a possible solution as well, we used that on some fittings and it’s lasted a couple years now

  3. Trying to decide if we should use the primer on the inside or just leave it as is? Your information has been super helpful, Thanks! Now that it has been awhile what would you suggest? How long ago did you prime it and how is it holding up?
    Cheers and stay cool!

    1. My recommendation is to use the white primer on the inside. It’s held up great, just needed a new coat on the bottom at the beginning of the season to get it nice and sparkling clean again before filling it. No peeling, no bubbles, no issues whatsoever!

  4. I used the primer on the inside as recommended, made sure to sand and used vinegar to get the galvanization off too but within 24 hours of filling our tank the paint began to bubble in areas. Not sure what to do at this point but drain and sand the whole thing and start over with a different paint. Any suggestions??

    1. Oh no!

      How bad is the bubbling? There’s some areas on my tank where there’s a small bubble or two, but it hasn’t flaked off. It seems to be mainly areas where I didn’t do the surface prep well enough and some of the oil coating or a bit of dirt remained on the surface before I painted over.

      If it doesn’t actually flake off, consider leaving it for this season and sanding / repainting next season. If it starts to flake, then yeah, draining the pool, sanding it down, re-doing the surface prep, and trying again is the best option I can recommend.

      1. In the areas where the bubbling occurred it flakes off very easily. I’m considering a different paint option that I saw in another stock tank blog that is a 2-part Pro Industrial Epoxy from Sherwin Williams but I called them they don’t recommend it…any other suggestions for paint would be appreciated! Thank you!

  5. I wish I could find a stock tank near me in Brooklyn, NY. I’ve looked all over. Anybody know where to buy one? Home Depot does not carry here, they tell me. I thought maybe they could ship it to a local store, but apparently not. A stock tank would be a perfect solution for our backyard since local wildlife–raccoons–tore a plastic pool we had and we definitely don’t want to add more plastic to the landfill. Thanks for any suggestions/ideas. Liz

    1. Check Tractor Supply for a galvanized stock tank, you’ll probably not find one in Brooklyn but I bet NJ has one you could pick up if don’t mind making the drive.

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