Tuesday, July 9, 2013

Gooey Water Problems

After a recent cleaning of the tide pool, staff observed that rather than looking better, our water appeared cloudier and felt slimier than normal. This is discouraging after investing time and energy into cleaning. An Animal Care staff member observed that while the water looked dirty, the protein skimmer was unusually clean. This immediately suggested a cause for our problems.

With the onset of warm weather, visitors wear more sunscreen and skin care products. Even after people carefully rinse their hands, these products not only impact the water, but they may also harm the animals as products cause the animals to create more protective slime coats. Also, the sunny weather leads to more growth of algae and faster metabolism for the animals. Both of these factors make the water gunkier.

The protein skimmer is a rather mysterious apparatus in the back vat of our tide pool. It helps clean the water, but most of the time we take it for granted and don’t think much about how it works.

Most of the water purifying systems that we use are filters. Some kind of medium is placed in the path of moving water. The medium either physically sifts out stray bits of gunk, or chemically bonds to them, or it is seeded with good bacteria that digest toxins out of the water and turn them into less harmful substances.

The protein skimmer works a little differently. The materials it captures are proteins, dissolved in the water that resists other types of filtration.

If you’ve ever beaten an egg white, you know that proteins in solution tend to form stronger, more lasting bubbles than water alone. The protein skimmer takes advantage of this fact by blowing a stream of minute bubbles through a column of water. The bubbles capture the dissolved protein as the rise up through the water. Once they get to the top, they are trapped in a cup. Over time, of course, they pop. The gooey sludge from the popped bubbles is all the waste protein that was formerly in the water. We clean the cup, and say “goodbye” to the mess.

So, how did the protein skimmer break? Answer – it didn’t, not exactly.

The bubbles in the skimmer are made by something called the Venturi effect. As water is pumped into the protein skimmer, it passes through a narrow area. When it does this, it accelerates and creates a low-pressure area. A tiny air tube set into the water pipe takes advantage of this lower pressure, and air is pulled into the water stream. There the turbulence of the water turns the air into bubbles.

When the tide pool was being cleaned, the protein skimmer was also cleaned. Before it was turned on, the air tube became waterlogged. Some of the salt from the water settled out of solution and became crystals, which partially blocked the tube.

The problem was easily fixed once we found it. We drained the protein skimmer, pinched closed the air tube and restarted it. The low-pressure area was able to pull the water and the salt out of the tube and airflow began again.

Hooray! Geekitude saved the day.

The protein skimmer is hard at work again. It has to make up for lost time, but it is happily collecting protein and making our tide pool water clean.

1 comment:

  1. Thank you for explaining the process to us. I never gave it thought as to how you keep the water clean! It is quite the process.