FAQ Topic

How to deal with fouling (marine growth)?

In certain environments organisms such as barnacles and algae can start growing on the SediMeter. The photos show what can happen in the perhaps worst possible case, a shallow tropical sea, between coral reefs and the shore.

Fortunately, even in this extreme case the lowest 10 cm or so remained clean. It is apparent that the leaves and sand grains that got swirled around by the waves prevented the organisms from getting a foothold.

Day 0: At 6 m depth in 27 ºC with no anti-fouling treatment. Off Cape Florida outside Miami. Past beach replenishment projects, and nutrients from land, probably contribute to poor visibility.	Day 24: Algae and barnacles cover everything except the lower part of the sensor.
Day 24: Close-up of the sensor. Enough backscatter detectors are still visible for it to continue measuring the bottom level. No biofouling occurred on the sensor inside, only on the outer holder tube.	2 m depth, same area, day 9: This sensor also escaped biofouling in the lowest section. The photo was taken on a relatively calm day, and still sand grains swirl around the sensor with every wave. It appears this kept it from biofouling.

Bio-fouling is not a problem in all places or at all times. For instance, several monthts of deployment under the ice in a temperate lake, at 2 m depth, produced no bio-fouling whatsoever. The same for 2 summer weeks at 21 m depth in the southern Baltic Sea. For fouling of benthic fauna to occur, there must be an event of larvae settling. In some waters this only happens once per season, but in tropical waters it happens all the time. For fouling of algae and slime (which depend on photosynthesis) to occur, there must be sufficient light.

Anti-fouling Paint: A solution, if fouling is a problem, may be to apply a transparent anti-fouling paint. There is no need to paint the sedimeter sensor itself, only the replaceable holder tube (and of course the light sensor if one is present). Note that the paint has to be clear, and no compound containing copper in any form that we have tested so far is clear, even if the name includes the word "Clear". As the availability of transparent anti-fouling paints varies with country, we advice you to contact local suppliers. A tip is to look for spray paint intended for aluminum lower units and propellers, or a clear waterline paint. A paint that works well, but which is now off the market, is Clear 25.

Cleaning Device: Another solution is to deploy a cleaning device. We are at present working on the development of a cleaning device for the SediMeter. Check back for updates, or contact us for more information.