Perhaps someone can shed some light on a marine growth situation that I am experiencing.

This summer, I installed a sea strainer on the raw water intake line of a reversible cycle heat pump on my boat. This was meant to prevent the problem of trash entering the system and clogging the small, magnetic-driven impeller pump.

The thru-hull of the intake is fitted with a rectangular scoop strainer with a bronze, perforated screen. The perforations are about 2mm in diameter. The screen has been checked and is intact.

I find that running the unit constantly for two weeks causes the new, quart-size strainer to completely clog up with both marine plants and animals. Particularly noteworthy is the accumulation of sea squirts, a jelly-like animal that is frequently found on pilings in salt waters. Now, these 34-long critters cannot enter the system because of the small diameter holes in the scoop strainer. This means that they must enter as minute beings and grow to full size in two weeks.

I suspect that constantly circulating water through the system promotes such rapid growth because other intakes, such as those for engines, do not seem to be affected, and they have even larger thru-hull strainer openings.

While it now appears that my new strainer addition was a bad idea, I am interested in knowing if such rapid growth has been well-known in the marine science community and if it could be expected to subside in the winter months in Tidewater. It also occurs to me that perhaps this growth is the result of warmer-than-usual waters and/or diminished pollution.

The vessel is kept in Little Creek Harbor, a tributary of the lower Chesapeake Bay.

Woody Holton
Virginia Beach, VA