Inflatable Spa Ozone Generator (an Absolute Must)

I absolutely love my hot tub. It's a great way to unwind after a long day of hard work and because it is inflatable I can store it away and it doesn't take up all of my patio. What I don't like is when I forget to drop some Chlorine in and it goes mucky, or I get spa mold (which laughs in the face of Chlorine), or the water gets too old and I have to change it...

I spent a bit of time (not a lot, mind you) browsing and the key differences between the filtration system of an inflatable tub vs a solid one are that they usually come with a bigger paper filter, a UV tube, and an ozone generator. I had a look at the costs of these units for a regular hot tub but they were too expensive for me, so I bodged an ozone generator and it's been working wonderfully well!

Since the unit has been running (several weeks), the water has been as clear as crystal, I barely need to put any Chlorine in the water, and the filter seems to have less muck.

Here's how to make one yourself!

For this instructable, you will need the following:

• Home ozone generator (I got this one from ebay)
• Plastic food container
• Drill
• Soldering Iron

Okay, so I lied a bit. We aren't making an ozone generator from scratch, but modifying one so that it's happier living outside. While the principal of operation is relatively easy, I don't like mucking around with the mains all that much!

Unfortunately I don't have any photos of the original case for this one, but it should be relatively straightforward. Unscrew the case and all the parts from the inside. Save the screws for mounting in the new enclosure.

The mechanical timer is a great idea if you were using this in the home, but when we want it to look after the hot tub for us we don't want to have to keep going out there to reset it. Snip the wires to the timer, then strip and join them together to form a loop. Cover any exposed wire with electrical tape.

Ideally I'd like to seal the whole box unit and only have the power and air holes, but the air pump doesn't seem to have an obvious "inlet" hole. What I've done instead is drill a series of small holes along what is to become the bottom edge of the unit (I'll be mounting it portrait). The power and air holes will also come out of this side, effectively stopping most splashes and rain from getting inside the container.

While it's not absolutely necessary, it's better to seal these holes to ensure large drops/splashes/fingers don't get inside and electrocuted. Take some sealant and smudge it all over the holes, inside and out. I placed a spare section of tube over the air outlet to ensure it would be accessible later.

Mount the unit portrait with the holes facing down against a wall or other vertical surface. I'd recommend as low as possible to help prevent people's splashing or bubbles from entering the unit. I've got mine plugged into a waterproof outside extension socket through a 24 hour mechanical timer, set for one hour a day. As this unit puts out much more than a regular hot tub ozone generator, it shouldn't need to be on all the time!

Connect the air line to the unit and drop the stone into the tub. Now go put your feet up - you're done!

Here's some things I'd do if I gave this another shot:

• Make all power and access holes at the bottom of the unit for a cleaner look
• Spray the tub a nice colour
• Find out where the air inlet is on the pump. Make a new case with no air holes at the bottom but one at the back which leads directly to the air inlet. Seal around the inlet.
• Find a way to tap into the water pump supply line of the hot tub, so we don't have to drape the air stone over the side.