Cold water cut into coral stone

Coast: the machine does all the work

Zanzibar and Dar never really cool down, so a plunge here is fighting warm humid air around the clock. We insulate the shell and the base, fit a lid light enough that people use it, design shade into the layout, and only then size the chiller — which is a step up from a temperate figure.

The plant gets a sealed, filtered enclosure so the condenser breathes filtered air rather than salt aerosol, and every metal part in the water circuit is titanium or A4 stainless.

Highlands: the climate helps

At Moshi and especially on the Ngorongoro rim the nights do most of the work. A shaded insulated tub there holds low temperatures with a small machine or, for a 14-16 °C plunge, none at all.

It is the one part of Tanzania where we regularly talk clients out of a compressor.

Coral rag, hardwood or built in

A basin cut into coral rag is the most Zanzibari thing we build and it looks like it grew out of the plot. It needs a waterproof substrate behind the stone — the coral is the finish, not the tank.

Oiled hardwood on a deck is the movable option and the fastest to install. A built-in microcement basin is the commercial answer. All three need insulation, a drain, circulation, cartridge filtration and ozone or UV on anything shared.

In short

• Coast needs a chiller year round; the highlands often need none
• Insulated shell and base, a usable lid, and shade designed into the layout
• Titanium heat exchanger and sealed filtered enclosure at the coast
• Coral rag is the finish, not the tank — there is a membrane behind it