Could someone help me identify this please.

[EedwinW]

ChemiClean will work well on this. Also check phosphate levels and verify TDS from your water.
Are you using Tap or RO water ?

Tap water, what is TDS

 

[vetteguy53081]

Tap water, what is TDS

Total dissolved solids (TDS) is a measure of the dissolved combined content of all organic and inorganic substances present in a liquid in a molecular or ionized or micro-granular suspended form. TDS concentrations are often reported in parts per million (ppm).
Water TDS concentrations can be determined using a digital meter which many pet stores should have and can test for you.
Tap water no good and likely the reason you are getting this. You will need to switch to RO water or even distilled to prevent this in the future