Pro Tips
A few helpful tips we received from other users
1. Recycle your water
Using water straight from the tap means there aren't any chemicals in it (as opposed to your standard jacuzzi or swimming pool). Which means you can use the tub every freaking day and your skin will never get dry and crackly like it does from chlorinated water. The downside of course is that untreated water gets funky after a while. We drain our tub every other day and refill (fortunately we are on a well so our water bill is $0, and we do not live in a drought-prone region). But this process has a silver lining too! Since the water is untreated we can re-route it. I run a length of hose from the drain spigot to two small apple trees we have near the tub so we get multiple uses from our water. If your tub is near a garden you could absolutely hook up a drip system to take full advantage of this feature.
Alternatively, if you’re close enough to a power source, you can purchase a circulation pump/filter for the tub to keep the water clean and avoid changing out the water altogether.
2. Stir the pot, slow the fire, use the drain
Hot water and cold water stratify, so you’ll need to stir your tub a few times while it’s heating up or you’ll have a layer of 110-degree water on top and 60-degree on the bottom. After you’ve stirred it well, and the overall temp is nearing 90 degrees, avoid the temptation to pile on the wood. The hot water heats exponentially, so that last 12 degrees to a perfect 102 goes really quick and you’ll shoot past it in a hurry. This is also where the drain spigot comes in handy. Most nights we end up at 106 despite our best efforts and have to drain an inch off the tub and pipe in some cold water to get the balance right.
3. Use good wood and next-day use
The better your wood, the less time it’ll take to heat your tub. If you’re lucky enough to have access to good hardwoods like maple or oak you’ve got it good. Here in North Idaho the best firewood we have access to is tamarack (larch), Douglas fir, and some birch. Lodgepole pine is pretty decent and I’ll burn it if I’ve got it. Grand fir and bull pine are barely worth the trouble to cut unless that’s all you’ve got. I find it takes four or five pieces of good Doug fir cord wood split into 2” pieces to heat our tub from cold. It takes half the time or less when reheating the next day because our insulation keeps the water between 85-90 degrees in the summer (TBD in winter). If I start a small fire after we get out of the tub at night, the water is often still close to 100 degrees the next morning.
4. Take fire and burn safety seriously
The Chofu is remarkably efficient and rips a hot fire in short order. Once it’s really going, secondary combustion kicks in—that's when the heat of the fire is strong enough to ignite and burn off the smoke generated by the wood—and it burns really clean, generating almost no smoke. We’ve never seen sparks coming out the top, but we do get the occasional bit of ash floating down. Because of this, we may purchase the optional chimney cap to prevent anything hot floating into the trees.
The chimney, on the other hand, will burn the shit out of you. This was part of the reason we left the back corner of the frame open. This feature creates an intuitive visual and spatial barrier for anyone seated on the back of the frame, discouraging folks sitting too close to the chimney.
And there you have it. If you've read this far, you're all the wiser for it. Maybe even ready to get building your own DIY hot tub. Just remember, measure twice cut once. And many hands make like work!