at my little retreat down at the lake, the beds are set up at 4 1/2 inches(3 2x4s). i have only slept on them twice so far, but i noticed this time that my urine was very cloudy(we guys have the advantage in this). foam is excessive protein in the urine. you will note that mercury is quite damaging to the nephritic tissue. sounds to me like mercury is making its way out.