Our float tank at Wellness & Recovery Haus in Kiama contains approximately 500 kilograms of dissolved Epsom salt (magnesium sulphate) in around 1,000 litres of water. The concentration creates a solution dense enough to support anybody effortlessly. But the role of magnesium in a float session extends beyond buoyancy. Here is what the evidence says about magnesium, how float therapy works, and what you can realistically expect from a session.
Epsom salt is the common name for magnesium sulphate, a naturally occurring mineral compound of magnesium, sulphur, and oxygen. It is named after the town of Epsom in Surrey, England, where the compound was first distilled from spring water in the early 1600s. It dissolves readily in water and has been used for centuries in bathing, agriculture, and medicine.
In float tanks, magnesium sulphate serves two functions. It creates the high-density solution required for effortless flotation, and it introduces magnesium into the bathing environment. Magnesium is an essential mineral involved in over 300 enzymatic processes in the human body.
Magnesium is involved in muscle and nerve function, blood glucose regulation, protein synthesis, and bone development. It also plays a direct role in the nervous system's stress response: magnesium regulates NMDA receptors and supports GABA activity, both of which are associated with relaxation and sleep.
Magnesium deficiency is common. The Australian Bureau of Statistics has noted that a significant proportion of Australians have inadequate dietary magnesium intake. Symptoms of low magnesium include muscle cramps, disrupted sleep, anxiety, fatigue, and difficulty concentrating, many of the same complaints that float therapy clients report improvement in after regular sessions.
This is the most contested question in float therapy science. The evidence for meaningful transdermal magnesium absorption is limited and mixed.
A 2017 study published in Nutrients found that magnesium can penetrate intact skin, but at relatively low rates under normal bathing conditions. A separate pilot study examining float tank sessions specifically found elevated plasma magnesium levels in participants after floating, suggesting some absorption does occur in the high-concentration environment of a float tank. However, sample sizes in these studies are small, and the findings have not been definitively replicated.
What this means practically: the physiological benefits of float therapy, reduced cortisol, improved sleep, and muscle tension relief are well supported by research. Whether transdermal magnesium absorption contributes significantly to those outcomes, or whether they are primarily the result of sensory deprivation and the weightless environment, is not yet clearly established. Both mechanisms are plausible and likely synergistic.
Possibly, but this should not be the primary reason to book a float. The relaxation, decompression, and mental reset benefits are well established regardless of how much magnesium is absorbed. Think of potential magnesium absorption as an additional benefit, not the main mechanism.
Magnesium sulphate is generally well tolerated. If you have kidney disease or are taking medications that affect magnesium levels, check with your GP before booking.
The concentration of magnesium sulphate in a float tank is far higher than a typical home bath, and the flotation environment itself, sensory deprivation, zero gravity load, controlled temperature, produces effects that a standard bath cannot replicate.
Most clients report noticeable benefits from a single session. For sustained effects on sleep, anxiety, or muscle recovery, floating once or twice a month is typical.
Wellness & Recovery Haus is located at Shop 8/65 Manning St, Kiama NSW 2533
View our Floatation Therapy service page for full details and pricing.
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