Skimmers and Plankton

Despite my skimmer runnung 24/7 and producing very satisfying amounts of brown gunk it appears that plankton levels are unaffected. Common knowledge has it that skimmers remove plankton - it makes sense, it seems logical and therefore it must be true!

However, after reading a post in another blog where a temperate reefkeeper in Oregon, USA, employed a skimmer to remove plankton blooms from his tank with little or no success I began to wonder if plankton is somehow 'immune' from skimmer uptake. It may be worth examining skimmer gunk under a microscope to see if it contains live plankton. I have no doubt that soluble proteins are taken up by the skimmer, but if live plankton doesnt fall under that category, if plankton does not 'stick' to air bubbles and simply passes through the skimmer unharmed - this has major implications for all reefkeepers. It explains how coralline algal growth is able to colonise tropical systems despite heavy skimming, how squirts and those tiny little tubeworms are able to multiply and cover the backs of all those rocks and how undesirable algaes are able to spread.

If skimmers do not remove plankton then they have no apparent drawbacks whatsoever. At least in any system that requires plankton to feed filter feeders such as bivalve molluscs, non-photosynthetic corals and fan worms.

Perhaps native reef aquariums, benefitting from regular re-seeding of plankton from fresh seawater under optimum conditions may find that the keeping of soft corals, bivalve molluscs and other filter feeders may prove relatively easy. If native planktonic organisms are able to reproduce and thrive in our aquariums despite heavy skimming - as appears to be the case - it seems that it may well be worth considering using a plankton tow net and specifically looking to capture plankton to add to the aquarium in the hope that desirable plants and animals might therefore be propagated.

If plankton growth is a problem, green water etc, adding more filter feeders might prove the best way to control water clarity. A full - grown mussel filters 4 1/2 pints of water a day, adding a few dozen to a geen tank might prove far more effective than upgrading a skimmer.