Calcium reactor media two better then one

[RGibson]

I have been testing a media mix in by geo 624 calcium reactor,the lower half Korallith with 6-10 mm grain size,top half Gen x crm media,using this keeps the ph up at night when the lights are off at a PH of 7.86 no kalkwasser or other additives are use to do this.Day time ph 8.2,alkalinity 150 ppm calcium 400 ppm.The ph from the reactor 6.83.