Stainless steel is a steel containing at chromium, nickel, chromium, the rest is iron, which gives it exceptional properties:

• Corrosion resistance: Chromium forms a protective oxidation film that protects steel from corrosion;
• High temperature and environmental factors;
• Mechanical strength: despite its light weight, stainless steel is durable, very strong and resistant to mechanical impact;
• Hygienic: Stainless steel is resistant to bacterial growth, making it hygienic and easy to disinfect and clean, making it ideal for ice baths or hot tubs.

There are multiple grades and classes of stainless steel, each with a slightly different composition of alloys. These chemical differences create slightly different physical characteristics.

AISI 316 (V4A / EN 1.4401) or AISI 304 (V2A / EN 1.4301 )

AISI 316 (V4A / EN 1.4401) contains 2-3% molybdenum. Molybdenum makes the material more resistant to corrosion, especially in salt water, acidic, chlorides environments. Stainless steel AISI 316 is higher resistance to high temperatures. If you plan to use salt, chlorides, acidic or you’re planning to place TenSpa products near the sea you should choose AISI316.

AISI 304 (V2A / EN 1.4301 ) is a heat and corrosion resistant steel. Solutions with as little as 25 ppm of sodium chloride can begin to have a corrosive effect. The big advantage of AISI 304 is the lower price. You can choose it if you do not use any seawater, chlorides or acidic environments.

Stainless steel has the innate ability to form a passive layer that prevents corrosion. The secret?

Chromium.

The chromium found in all stainless steels reacts quickly with oxygen environments, much the same as iron. The difference is that only a very fine layer of chromium will oxidize (often only a few molecules in thickness). Unlike flaky and unstable iron oxide, chromium oxide is highly durable and non-reactive. It adheres to stainless steel surfaces and won’t transfer or react further with other materials. It is also self-renewing—if it’s removed or damaged, more chromium will react with oxygen to replenish the barrier. The higher the chromium content, the faster the barrier repairs itself.

Once oxidized, or passivized, stainless steel typically rusts at a very low rate of less than 0.002 inches per year.

However, please be aware that stainless steel may be susceptible to rust. But please note these rusts you could clean very easy

• Chlorine content: max 3.5 mg/l (ppm)*
• pH value: 7.2–7.6
• Alkalinity: 60–120 mg/l (ppm)
• Calcium hardness: 100–300 mg/l (ppm)
• Iron: max 0,1 mg/l (ppm)*
• Copper: max 0,2 mg/l (ppm)*
• Manganese: max 0,05 mg/l (ppm)*
• Phosphorus: max 0,01 mg/l (ppm)*
• Nitrate: max 50 mg/l (ppm)*
• Chloride (salt) content: max 250 mg/l (ppm)
• Chloride (salt) content: max 35 000 mg/l (ppm) – titanium for salt water

• The stoves are specially designed for the hot tubs or small pools
• Maximum acceptable water temperature in the hot tub is 45 degrees
• It is not allowed to close the input and output pipes of the stove during the burning and until the stove is cooled down
• It is not allowed to create extra pressure in the stove
• It is not allowed to let the water freeze in the stove
• It is not allowed to let the water freeze in the hot tub
• It is not allowed to use the stove without water inside the hot tubCorrect and incorrect connection of the external stove-The external heater and outdoor hot tub must be placed on a flat, solid surface.It is important that the connection hose at the top connects slightly (with a little angle).

  -The lower stove connection hose can be connected evenly.

  CAUTION! Never burn the stove without the required amount of water in the hot tub. Otherwise, you may burn the stove and hot tub.