This sporadic column (contact the editor if you want to see it more often — suggestions for topics are welcome) is about how you can save money and still live a “greener,” more responsible lifestyle locally.
We’ve covered solar power, electric vehicles and rainwater harvesting so far.
Now most of you probably think of hot tubs as essentially wasteful and hardly “green,” but I’m here to tell you that they don’t have to be.
Years ago, I actually made a hot tub out of a 300-gallon stock watering tank. Cost then: maybe $500. I set it up on concrete blocks and put a three-burner portable propane “stovetop” under it.
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It heated up fairly quickly, although draining and cleaning it posed a problem because the drain hose was very narrow.
About five years ago, I started looking into Softubs, which I’d seen demoed at home shows.
The advantage of Softubs is that they are easily portable (can be rolled when the external motor/pump is removed) and they are not heavy at all, because they are mostly made of vinyl and foam.
But the new cost was $3,000 to $4,000 for units between 6 and 8 feet wide, and I couldn’t afford that. So I started looking at Craigslist for a used one and, lo and behold, I saw two available for around $1,000 to $1,300 each and bought them both. (Silly me. I later sold the extra one and got most of my money back.)
Softubs are heavily insulated (the sides are about 4-inches thick). When they get to the desired temperature (104 degrees max), the electric pump motor shuts off (there’s a thermostat).
Now, I’m sure you’re saying, “Well, electricity is expensive,” and it certainly is, but the company advertises that keeping a Softub hot may only cost around $25 a month. I’ve found that to be true, and mine is in the woods!
I’ve added extra insulation on the bottom of the tub and 1.5-inch foam over the cover, which can be slid off conveniently. I also have a floating plastic “solar” blanket underneath the lid. Overall, these strategies really keep the water toasty.
Recently I went away on a one-week trip, turned the tub off (which was 100 degrees), and a week later the water was still at 78 degrees (and again, it’s outside)!
I think that’s simply amazing, don’t you?
Cleaning Softubs — at least these older models — is problematic, as there is no drain. But it wasn’t too hard to install one using 1-inch PVC, Goop and a valve. I try not to drain it any more than necessary, but when it is necessary, the water goes on plants or trees. Using some chemical conditioning like shock keeps the water clear for a long time. I avoid over-using it; I can actually fill the tub with rainwater from my roof rainwater catchment system, although I was beginning to run out late in the fall as our town became ultra-parched.
If you want to be ultra-efficient, you might consider powering this up with solar. I believe (but have yet to prove) that a couple of fairly large, say 200 watts or so, solar panels and a few deep-cycle batteries might keep it going indefinitely.
Remember, the motor/pump only runs when the water is being heated — and it is water running around the motor that actually heats the tub. That’s similar to a fridge in a sense — the motor only runs when the inside temperature starts to rise above the cooling settings (so there isn’t a continuous draw).
I haven’t had any maintenance issues in all the time I’ve had the tub(s).
So if electricity is not really an issue, and the water is conserved and ultimately recycled, that’s about as green as you can get, right?
If you want to see this demonstrated (it’s inside a 14-foot-wide geodesic dome I built with 2-by-4s), I’ll give a tour some weekend. Send me an email to sign up, subject heading Green Hottub.