Jack, you're correct and the care instructions for it state to:
Periodic cleaning (three to four times per year) is
the primary maintenance required. </span>Alpha
Systems recommends using a non-abrasive household cleaner, such as Top Job or
Spic-N-Span, and a medium-bristled scrub brush.
use any harsh or highly-abrasive products during cleaning. </span>When finished cleaning, remember to thoroughly rinse the roof and
sidewalls in order to remove any soap residue and to prevent streaking. </span></span><b style="mso-bidi-font-weight: normal;">CARE
SHOULD BE EXERCISED WHEN WORKING ON TOP OF YOUR UNIT! </span>THE ROOF MAY BECOME SLIPPERY WHEN WET.
<?: prefix = o ns = "urn:schemas-microsoft-com
<b style="mso-bidi-font-weight: normal;">DO NOT USE
ACETONE, OR ANY OTHER PRODUCTS CONTAINING PETROLEUM DISTILLATES, ON THE ALPHA
SYSTEMS ROOF MEMBRANE. </span>USE OF THESE
PRODUCTS WILL DAMAGE THE MEMBRANE.</span>[/b]