Just noticed a problem with 2 of my acros todat. Seems like tgere is a white string mat on a small part of 2 acros. Best way i can describe it is that it looks like frayed nylon string just blowing in the current. About 1/4 inch in length. They are bot located on the sode of the acro closest to the side the current is coming from. Any thoughts? I doubt its too much flow, but who knows.