I Converted Our Giant Hot Tub Into A Cold Pool For The Summer

It’s summer. It’s hot. The backyard is where it’s at. So, I got us a pool! We already have a giant 10-person jacuzzi taking up space, so why not put it to use to cool us down when it’s toasty and we aren’t leaving the house to go anywhere? Why do we have a giant jacuzzi? And How did I convert it? I’ll tell ya.

To back up. Our house came with the 8’x11’ hot tub when we bought it. Apparently, the previous owner wanted a pool, so he got himself a 10-seater hot tub to satisfy his thirst for a giant body of water that he could dunk himself and nine of his friends in.

When we were negotiating an offer on the house, we tried to get the owner to remove the large tub taking up a quarter of our yard. We knew we’d never use it and it was such a prominent part of our outdoor space, that we simply wanted it gone. We didn’t manage to negotiate it out of the sale, but I was always grossed out by it. Our house was smelly and filthy so I assumed this hot tub was icky and didn’t want to submerge my body in it. However, it was all in my head. It could be cleaned, just like our house was deep cleaned.

Anyway, as the years went on, we just lived with the giant thing in the yard. When my friend Natalie came over to paint it black with me a couple of years ago the thing visually receded into the back fence and it wasn’t so much of an eyesore. I got over my distaste for it, but I still want it gone. Just imagine what I can do with that space! I could use those 88 square feet for veggie beds, or trees, or a dining space, or anything!

At some point a few years ago I decided I’d put it to use. I’d embrace the hot tub! We had it professionally cleaned (which honestly is just a guy using Simple Green with a sponge), purged all of the filters and jets clean, then filled it up. We turned it on and heated it up thinking this would be a relaxing end-of-day activity for us. But I just didn’t fall in love with it.

It had to be turned on constantly to keep the water hot, which took a ton of energy for such a giant tub, and the motor was noisy. I found a model number and learned that the jacuzzi is 20+ years old, so it’s not the most efficient or quiet thing to operate. It wasn’t fun to have it buzzing all day long, and it wasn’t fun to have the whirring noise while I sat under the stars in the hot tub. I think we used the hot tub maybe twice and then stopped.

After it sat for a month, we realized we’d never use it again, so I opened up the lid to let all of the hot tub sanitary chemical dissipate, then I covered it back up. I made a mental note that I’d drain it in the summer when the garden could benefit from all of that water. (Draining in the rainy season of San Diego is just silly when we have summertime droughts and the plants would love my rejected hot tub water.) But somehow I forgot. And the water just sat there. I remember in the spring I added mosquito dunks to keep those pesky bugs from making a home in there. (Side note, those things are amazing and necessary in rain barrels or any water that isn’t treated or circulating! You can read about how I prevent mosquitos here.)

And this brings us to summer 2020. The backyard became the dumping ground for all of the construction debris over the last few months with salvaged lumber piled everywhere. Believe it or not, this is actually after three hours of cleaning and removing a bunch of wood. I spent an entire weekend just cleaning before I could get to the pool business.

Anyway! You came here to learn about converting a hot tub into a cold pool. Let’s get into it.

The next image isn’t my proudest photo I’ve shared on the internet. I do need to remind you that this water sat in the jacuzzi for a couple of years. It looks gross, but hey, it’s just natural dirt and grime!

The cover to the hot tub has lots of gaps for the nearby plants, dirt, and slugs to make their way into it. Here’s what I did (in summary) plus some good cleaning tips even if you don’t have a hot tub.

How I Cleaned My Hot Tub:

1. Drain the hot tub - You could use a sump pump to quickly get the water out, but I was in no rush, so I passively drained it. I used just a simple garden hose and the magic of siphoning to get it out. Here’s a brief video on the simple steps I took to drain the water.

2. Clean the surfaces - I didn’t want to spend all day scrubbing the giant tub by hand. Enter the scrub brushes that attach to a power drill! These things are game-changers for cleaning anything and everything with less time and less arm energy. You can also get scouring pads on your drill, too. Hello tile cleaning ease!

3. Purge the lines - There’s a product called Spa Purge that you dump into the water and let it circulate. It flushes the filters, jets, and all of the hidden plumbing. Because my hot tub was initially so filthy in the main compartment, I didn’t want to introduce this grime into all of the jets and hoses. So I drained it, refilled it, purged it, then re-drained it. Luckily, my plants enjoyed this grimey water! If you have a hot tub in need of deep cleaning, you could purge it first (assuming it wasn’t full of gunk), drain it, fill it, then enjoy it and skip the extra drain and filling that I did.

4. Refill the water - Just pop in a garden hose and fill it up! I do recommend timing how long it takes to fill up (down to the second). Turn the hose on full blast then as soon as you drop it in, set the stopwatch on your phone or your real-life stopwatch. As soon as it’s done stop the clock and calculate how many seconds it took. Then, do the same technique with a 5-gallon bucket. Divide the number of seconds it took to fill the bucket by 5, then divide the hot tub number of seconds by this new number the seconds. That number is the gallons in the hot tub. You can use this number to understand how many chemicals to add to keep the water sanitized.

5. Treat the water - I’m using bromine tabs in a little floater then using test strips to balance the pH up and down.

6. Maintain the water - We circulate the jets occasionally and we shock the water after we use it.

7. Use it as a pool instead of a hot tub - Simply don’t heat it! That’s it. As long as you treat the water and circulate it the way you would a hot tub, it’s safe to dunk your human body into. During my initial research, I saw that people can buy adapters to cool their jacuzzi water, but I don’t see a need for that. The natural water is perfectly chilly (almost too chilly?) for dunks on a sunny afternoon.

I’m sure I’ll get some Qs, so here are the As:

Does it need to be treated?

Hot or cold, the water can pick up bacteria from people/sunscreen/sweat/clothes/etc. so keeping it clean is important. I learned a lot about cleaning and maintaining a hot tub (or a pool) from this YouTube channel. I watched his spa videos and his pool videos to determine that the treatment is basically the same. He does include way more info than I did, so check those videos out for more details.

I’m not into pool chemicals, what’s the solution?

I decided that Bromine is a less irritating pool cleaner than chlorine, so I chose the least noxious option for this pool. It’s not perfect, nothing is, unfortunately.

I considered not putting chemicals in the water at all, actually. I was inspired by a homeowner on the Green Homes Tour that converted her in-ground pool into a pond. She stopped using chemicals, turned off the filters, then let nature take over. It’s an algae, fish, and plant-filled oasis. She even swims in it! BUT. The different between what she did and what I did by leaving my jacuzzi to sit for a year, is she added aquatic life that creates an entire ecosystem in the pond. I decided that I didn’t want to add fish to my pool, so I decided not to do this. Click here to check out my post I wrote about it.

That’s a lot of water to drain and waste!

Yeah, it’s a lot of water. But, when I drained the water it fed my plants during a drought, and they loved it. As for the water filling, it does feel like a ton of water, but it’s the equivalent of about 15 fifteen-minute-long showers. Let’s just say that during quarantine, I’ve skipped the equivalent of 15 showers.

What will you do when it’s not hot enough for a cold pool anymore?

Oh you know, I’ll probably just let it sit and get disgusting and then repeat this process again.

In San Diego, it’s hot until October, so we have many more months to enjoy the pool. Hopefully by the end of this hot season I’ll have a plan for the backyard and can set the groundwork for finally getting rid of the hot tub. The goal is to turn the space into an urban garden! Fingers crossed we can start this soon-ish.

And here we are now! Margaritas are extra refreshing in the cold pool when summer temps heat up.

The retro lounge chair was gifted by my mom from her garage. I used to lounge around on these very chairs as a kid! While mine are heirloom hand-be-downs, I found oodles of 80s/90s plastic pool loungers in multiple colors on eBay. Might I need to start a collection?