Get a rake and spin it like pasta. This is a normal occurance in spring and fall. Tell the client it happens and is totally natural. After the marginals and floaters begin putting on serious growth, the algae will begin to fade. I use a bacteria that has S.A.B (string algae buster) in it. Basically it has barley powder and BB that eat the sludge and debris in the pond. Def. clean out any leaves and old plants that maybe adding extrs nutrients to the water. The S.A.B. takes a couple of weeks to show real results, (barley activation)but after I added, the next day algae was floating to the top, where the skimmer and myself caught it. Don't worry, and don't drain the pond, unless you plan on keeping a few hundred gallons of water avail. New watermay harm any BB already there.