HOT TUB from a MILK TANK & wood fired water heater from a Back Boiler.

Описание: If an insulated stainless steel tank can keep milk cold then it should keep water hot, right?
I've always wanted a hot tub, we have a stream in our garden and I'm going to set this tub into the bank of the stream in our lawn. Large wooden tubs are expensive, they are hard to clean, maintain, and structuraly unsuitable for burying in the ground. Plus, where's the fun in just buying a tub compared with building your own?
I spent years considering an inexpensive alternative to the traditional wooden tub, cattle troughs, plastic tanks, IBC tanks, insulated concrete........
In 2013 the E.U. abolished milk quotas for dairy farming and since then dairy farmers have been upsizing which has resulted in an abundance of small (1, to 5,000L), food grade (316) stainless steel, insulated twin wall milk tanks for sale on Done Deal (Ireland's equivalent of Craigslist).
So after some patient watching, waiting, bidding and haggling I picked up a 2,000L (440usg) tank for €200, it's worth about the same in scrap value, a bargain, right?
That was a year ago, it's been sitting in my backyard since then (much to the annoyance of my better half). Then, the Covid 19 pandemic hits, work grinds to a halt, the sun shines for 7 weeks on the trot, and I'm at home with the kids doing the school work...... the perfect time to get stuck into my hot tub project, this is how it went...