If you used tap water, I wouldn't worry. It could be that you have hard water, and these are just particles of water hardness that have been precipitated out by dissolving the D-76. The main component of D-76, Sodium Sulphite, can react with water hardness to form these insoluble granules. If they don't amount to more than about half-a-teaspoonful in the gallon, then just filter them out, or decant off the clear liquid. It'll be fine.(posted 8207 days ago)
You could try changing to Ilford's ID-11, which has a water softening component incorporated.