Question
We have a backyard pond about 400 gal. The rocks on the bottom developed what appears to be a scale. The rocks are covered with this "scale"  Also, there are clumps of yellow-gold matter on top of the water.  The water is clear.  There are no fish in the pond, only water lillies and they seem to be okay.

Answer
Hello Judy. The scale you are seeing is organic build up common to water gardens. Sometimes it will grow rapidly or excessively if the pH is too high. Check you pH. There are bacterial clarifiers that will help rid of this too. You can find them at any pond supplier. Thanks for asking! Hope this helps.

Brigitte
www.pondmarket.com