General Hardness is a vital element in aquaira water management.  It is a mewasure of dissolved salts that aquatic life require and draw from the water.  Once depleted these salts need to be replenished.
 
Our Australian made GH Test kit has a shelf life of 12 months when stored cotrrectly in a cooldark place.  All of our test kits come packaged in glass recepticles rather than single use plastic.