Skimmers

[Jordan N.]

Going to give a somewhat contrarian view -- Here goes...

Two excellent articles about what skimmers actually do.
http://www.advancedaquarist.com/2010/1/aafeature
http://www.advancedaquarist.com/2010/2/aafeature]

The first article examines the TOC (Total Organic Compounds) removed by a skimmer. The second article does chemical analysis on the produced skimmate. Overall they found VERY little difference in the actual performance between any of the skimmers.

Our data show that there are not compelling or remarkably large differences in measurable skimmer TOC removal metrics among the seven skimmers tested, although the Reef Octopus 150 consistently underperformed compared to the other skimmers. However, in the larger picture, it is equally apparent that if an aquarist runs a skimmer continuously (24/7), then any of the skimmers tested would perform adequately in terms of rate of TOC removal; the only practical differences might involve the frequency of skimmer cup cleaning. A perhaps more interesting observation to emerge from these skimmer studies involves not the rate of TOC removal, but rather the amount of TOC removed. None of the skimmers tested removed more than 35% of the extant TOC, leading to the conclusion that bubbles are really not a very effective medium for organic nutrient removal.

The chemical/elemental composition of skimmate generated by an H&S 200-1260 skimmer on a 175-gallon reef tank over the course of several days or a week had some surprises. Only a minor amount of the skimmate (solid + liquid) could be attributed to organic carbon (TOC); about 29%, and most of that material was not water soluble, i.e., was not dissolved organic carbon. The majority of the recovered skimmate solid, apart from the commons ions of seawater, was CaCO3, MgCO3, and SiO2 - inorganic compounds! The origin of these species is not known with certainity, but a good case can be made that the SiO2 stems from the shells of diatoms. The CaCO3 might be derived from other planktonic microbes bearing calcium carbonate shells, or might come from calcium reactor effluent. To the extent that the solid skimmate consists of microflora, then some proportion of the insoluble organic material removed by skimming would then simply be the organic components (the "guts") of these microflora. These microflora do concentrate P, N, and C nutrients from the water column, and so their removal via skimming does constitute a means of nutrient export.

So according to this data skimming may function primary by removing diatoms and other small reef life --That sounds like food to me. Actually now that I think about it that may be why skimmate smells so bad --A cup of rotting life isn't going to smell very good.

Have you considered building a DIY turf scrubber and giving the algae a place to grow other than in your tank? If I remember correctly I believe Erik uses one.

-Jordan N.