Two different patterns of deposit formation at the surface of a membrane were predicted. According to the first pattern the thickness of the deposit increases along the channel, and the situation where the deposit is not formed at ail at some starting part of the channel is possible. According to the second pattern, the thickness of the deposit decreases along the channel, and a part at the end of the channel may be deposit-free. The conditions under which deposit-free parts begin to appear were determined, as well as the conditions under which the deposit is not formed at all but completely carried away from the channel.