Sooting (discoloring of fire glass):

Fire glass does not burn, so any discoloration is caused by the fuel being burned.  Discoloration of fire glass is usually caused in liquid propane (LP) installations due to the improper burning of the gas which causes sooting of the fire glass.  This is usually caused by a missing air/gas mixer prior to the burner, or an undersized air/gas mixer.

Soot on fire glass is easy to clean by rinsing the fire glass with a vinegar/water mixture (50/50).

No Yellow Flame:

Air shutter setting

Crack in burner gasket – check for leaks allowing air into the gas 

A yellow flame is achieved by allowing the gas to use some of the ambient air for combustion.  A lack of a yellow flame is caused by having too much air in the air/gas mixture.

To fix this problem reduce the amount of air mixing with the gas prior to the burner.  Typically, this is caused in liquid propane installations where the air mixture valve is oversized for the burner size.  You can test this by temporarily blocking some of air intake into the valve, if this solves the problem replace the valve with one with a lower BTU rating.

Crackling Sound from Fire Glass:

This typically happens when tempered fire glass is damp or wet and the burner is turned on.  The heating of the moisture causes an expansion as it turns to a gas which may cause some of the cracked (but not completely broken) pieces of tempered glass to separate into pieces.  This is a normal occurrence in new installations of tempered fire glass and is not a need for concern.  Once all the cracks in the glass are separated into individual pieces the crackling and popping sound will cease.  We do recommend that on new installations, if the glass is wet that you start off with a low flame and turn it up after the glass has heated and dried.  To completely prevent this you can keep your fire glass dry by covering your fire pit when not in use (be sure it has completely cooled down to prevent a fire hazzard).