Magnesium rod inserted in the inner water tank:Magnesium rod is usde in the water tank to clear the water.

Magnesium rod inserted in the inner water tank(non-pressurized):

Magnesium rod is used in the water tank to clear the water.

One side is fixed on vacuum tube,the other  side  inserts in the water tank of the solar water heater.

In the picture is 0.75 inches diameter.

Magnesium rod inserted in the inner water tank