Pond Boss Forums INTRO Questions & Observations clearing the water

First and foremost I want to welcome you to the forum.

Sheetrock does have some disadvantages as ewest linked to above. Often times the manufacturers use fiberglass shavings and other unwanted materiels that you do not want added to your pond.
Another approach for you might be the addition of aluminum sulphate. Around 5 lbs to the acre usually does the trick. When used in a greater quantity it could drastically change your pH levels, but in moderation it should do the trick.
I know Condello has worked with this product so maybe he can enlighten you further.

Good luck!