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I just sampled some skimmate after one month of operation, allowing for both liquid and sludge in the sample and from the inside and outside of the skimmer neck. A quick look under the microscope and there is a lot of activity - polychaete larvae, copepods, amphipods, nematodes. I stirred it into solution and will let it settle to see what creatures might come out. Then, I will filter the water over various microns of filter paper and determine the average particle size removed and then do an analysis on the water saving an aliquot for higher resolution analysis and freeze the sludge for mass spec ande other at -80C for analysis at a later date.
I should get good bacterial counts and biomass on another sample after filtering between 1 and 0.22 microns. I'll try and enlist a good microbiologist to help...any out there?
I'll do fresh bubbles as they are skimming, too.
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Eric Borneman
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wow all those things, - polychaete larvae, copepods, amphipods, nematodes, filtered out that could be food for the tanks inhabitants. is this another augument for going skimmerless? i am very interested to see the results.
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Carl-
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Sun powered reef
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| More than being food, they are also the next potential generation of detritivores... One thing I have noticed after going skimmerless is a much higher density of juvenile polychaets and stomatella.
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Today on filtering I found almost all of the material is retained on 50micron filter paper. I took some images of the material - almost all floculent material. I saved what was retained on 0.22 micron filter, and the remainder is dissolved material. I will post photos shortly as well as some quick tests and more explanation.
interesting is that in a vial for 24 hours, almost all the meiofauna died. There were still a lot of what appeared to be ostracods and a lot of ciliates still alive. The solution and sediments had a strong odor of hydrogen sulfide, but interestingly the 0.22 micron filtrate has almost no odor and a pale tea-color tint.
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Eric Borneman
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| Very interesting. I was wondering whether or not you could determine particle size. Is it possible that smaller particles stick together forming larger particles once in the skimate? What particle sizes did you filter for? Fred
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| Eric said he will eventually examine actual bubbles, that should provide some answers about aggregation in the collection cup. Eric, I was wondering if you'd provide us with the performance details (manufacturer/model/water flow rate/air flow rate/bubble size) of the skimmer you are examining? Also maybe some images of the skimmer in action and skimmate you are looking at?
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I stirred the mixture pretty well using a pipette but trying not to purposely break apart particles into anything smaller by mehcanical agitation. After the mix was dry on the filter paper and I removed the filtrate for further filtering, I used ddH20 to wash and see if the particles came apart. Under the scope, there is definitely some amassing of particles.
This was the largest pore size paper I had, so I need to use sieves, i guess.
After tha majority of particles were filtered, there was relatively little going down to 10, 5, 1 and 0.22 microns.
Those papers are drying now so I can weigh them.
I'll probably do a C:N analysis on them to see if the material removed varies much from detritus, algae, animal tissue, bacteria, etc.
Right now, after seeing this stuff after one month, I think it is going to be far more interesting to collect, say, the first 100ml out of a clean collection cup because the mud of a skimmer seems to be mostly detritus and bacterial breakdown products and may not at all represent the initial skimmate before it accumulates and settles in the top.
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Eric Borneman
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Sure, I can do that tomorrow.
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Eric Borneman
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| Another interesting thing to look at would be to filter, with a fine mesh, a proportional amount of water that is skimmed to make the 100ml of skimmate, so you can look at what is and is not skimmed out as well as how efficient the skimmer is with certain things such as specific larvae and detritus.
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Oh, exactly right. I'll be doing this after coffee.
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Eric Borneman
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