I have finally found some diatoms

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MichaelBrock
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I have finally found some diatoms

#1 Post by MichaelBrock » Mon Sep 24, 2018 7:14 pm

I carried a few sample vials with me on a trip this past weekend to the Jacksonville, FL beaches and at a restaurant near there I took a sample from the brick (and oyster bed) of an old boat ramp. I just did a quick check with a thrown together slide (dirty, reused slide and cover slip) and I think I finally have a sample worth trying to clean!
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MichaelBrock
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Re: I have finally found some diatoms

#2 Post by MichaelBrock » Mon Sep 24, 2018 7:15 pm

And a few more.
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Hobbyst46
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Re: I have finally found some diatoms

#3 Post by Hobbyst46 » Mon Sep 24, 2018 7:26 pm

Looks like a nice variety. Even centrics! and Pleurosigma (?). Good luck!
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KurtM
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Re: I have finally found some diatoms

#4 Post by KurtM » Tue Sep 25, 2018 12:28 am

Having gone diatom hunting myself a time or two, I'd call that a very promising initial glance! Do let us know how you get on with it. 8-)
Cheers,
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coominya
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Re: I have finally found some diatoms

#5 Post by coominya » Wed Sep 26, 2018 9:32 pm

Lots of diversity alright. When you say "clean" do you mean you will isolate the diatoms from all that extraneous matter on the slide, or are you going to conduct that complex procedure involving acids?

MichaelBrock
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Re: I have finally found some diatoms

#6 Post by MichaelBrock » Thu Sep 27, 2018 12:33 am

"Lots of diversity alright. When you say "clean" do you mean you will isolate the diatoms from all that extraneous matter on the slide, or are you going to conduct that complex procedure involving acids?"

Both! The process of cleaning breaks down the organic matter in the sample and diatoms. So if it goes well you're left with just the frustules. I'm going to try the heated Hyrogen Peroxide method with a pre-treatment of HCl. Basically this method without the potassium dichromate (I'm buying into the argument that it doesn't add anything to the process...mostly so that I don't have to buy any):

http://micrap.selfip.com:81/micrapp/cleandiatoms.pdf

Apparently 30% Hydrogen Peroxide is more difficult to find lately. All of the 30% and 35% hydrogen peroxide I was able to find on Amazon & Ebay has all been diluted to 13% or less. I'm the process now of attempting to make my own high % Hydrogen Peroxide with freeze distilling (having done it in homebrewing beers a few times).

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KurtM
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Re: I have finally found some diatoms

#7 Post by KurtM » Thu Sep 27, 2018 3:46 am

I use food grade 35% hydrogen peroxide obtained from a local health food store.

Getting rid of organic matter is a good thing for sure, but ending up with inorganic debris in our strews is largely unavoidable. Most of it will be in the form of super fine mineral "silt".

Incidentally, dissolving organic frustule contents is only part of the cleaning process; the other half is getting good separation of the valves. But you'll learn all these things quickly enough just by doing it. Have fun and report back - it's entirely possible all of us will learn something new from your fresh approach!
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Hobbyst46
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Re: I have finally found some diatoms

#8 Post by Hobbyst46 » Thu Sep 27, 2018 7:44 am

MichaelBrock wrote:...Both!...I'm going to try the heated Hyrogen Peroxide method with a pre-treatment of HCl.
May I suggest that you rinse the diatoms with DW in between the HCl and H2O2 treatments, two or three times - otherwise the residual HCl will destroy your H2O2.
Basically this method without the potassium dichromate (I'm buying into the argument that it doesn't add anything to the process...mostly so that I don't have to buy any):
Following a long, amiable and thorough discussion (thanks to members rnabholz, zzffnn, KurtM, photomicro and others) of the dichromate method in a previous post, I took the trouble to read the original article by the inventor of this method (van Werff). Van Werff attributed the cleaning to the strong reaction between H2O2 and dichromate, which rapidly heats the mixture (to about 80C), causing much froth. So, in line with others, I think that dichromate accelerates the cleaning, but if one boils the diatom in H2O2 anyway (I do so), the dichromate can be omitted.
30-35% H2O2 is best stored in the refrigerator (not freezer), to extend its shelf life.
I'm the process now of attempting to make my own high % Hydrogen Peroxide with freeze distilling (having done it in homebrewing beers a few times).
IMHO making high % H2O2 by "freeze distilling" (or by any other method) at home is not practical. The freezing temperatures of H2O2 and H2O are nearly identical.
If one cannot find 30% H2O2, I would try to eliminate most liquid from the raw unclean diatoms (filtration, etc) prior to the addition of the H2O2. Thus, my 13-15% H2O2 will not be further diluted.
Good luck!
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SunshineLW
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Re: I have finally found some diatoms

#9 Post by SunshineLW » Thu Sep 27, 2018 10:12 am

EDIT: I have posted a separate thread about this in the forum for "Specimens, samples, and slides." It is more complete and contains images: viewtopic.php?f=10&t=6467

I have never "cleaned" diatoms but I do know how to perform a fecal sedimentation, which involves isolating small, sinking, parasite eggs from the rest of the debris found in a stool sample.

There are several ways to perform a fecal sedimentation. There is a specific method for performing a fecal sedimentation, which I believe may be useful for diatom isolation ("cleaning").

The method I have in mind involves a device called a "Fluke Finder" (https://www.flukefinder.com). The Fluke Finder is simply a filter with two separate screens positioned one after another. Using it is as easy as adding water to your sample (making a soup), and running the sample through the pair of screens.

1. First, the sample runs through a coarse screen. All of the eggs pass through this coarse screen, but the larger debris does not. As a result, this large debris is caught in the coarse screen and is effectively separated from your eggs, which are small enough to have passed through.

2. Then, the sample runs through a fine screen. All of the eggs are caught in the finer screen, but all of the excess fluid is drained.

After running water through the screens several times, all of your eggs (or protozoa; ex., Giardia) are caught in the second finer screen and are ready for observation/ manipulation under the dissecting microscope.

The Fluke Finder is made for isolating eggs that are around ~80-200 micrometers in length at their largest diameter. I do not know the mesh sizes of the screens; therefore, I cannot tell you what is the smallest size of diatom that can be caught by the Fluke Finder. I know that diatoms can be only several micrometers in length, and I would guess that these smaller diatoms would pass through the finer screen; however, I'd be curious to see how the Fluke Finder (or a custom Fluke Finder) would function in isolating ("cleaning") diatoms. My hypothesis is that it could be used for isolation and concentration of larger diatoms found in large volumes of diatom soup samples.
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MichaelBrock
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Re: I have finally found some diatoms

#10 Post by MichaelBrock » Thu Sep 27, 2018 11:36 am

Hobbyst46 wrote:May I suggest that you rinse the diatoms with DW in between the HCl and H2O2 treatments, two or three times - otherwise the residual HCl will destroy your H2O2.
I will definitely do that. Makes sense
Hobbyst46 wrote:Following a long, amiable and thorough discussion (thanks to members rnabholz, zzffnn, KurtM, photomicro and others) of the dichromate method in a previous post, I took the trouble to read the original article by the inventor of this method (van Werff). Van Werff attributed the cleaning to the strong reaction between H2O2 and dichromate, which rapidly heats the mixture (to about 80C), causing much froth. So, in line with others, I think that dichromate accelerates the cleaning, but if one boils the diatom in H2O2 anyway (I do so), the dichromate can be omitted.
That's what I came away with from the discussion (I don't think there is any diatom discussion here that I haven't read a few times). I bought an old heat plate from eBay and it's my plan to boil it.
Hobbyst46 wrote:IMHO making high % H2O2 by "freeze distilling" (or by any other method) at home is not practical. The freezing temperatures of H2O2 and H2O are nearly identical.
If one cannot find 30% H2O2, I would try to eliminate most liquid from the raw unclean diatoms (filtration, etc) prior to the addition of the H2O2. Thus, my 13-15% H2O2 will not be further diluted.
Good luck!
I think the freezing point of H2O2 is only .4C lower. I tried the "freeze the bottle" approach from Youtube and only got a few drops. I'm now trying a better controlled process. I have a temperature-controlled freezer that I use for home brewing beer so I set that to -.2C and put the diluted H2O2 in a plastic container inside of a second container filled with frozen water. It has been going slowly but so far I have taken about 200ml of what I assume is water out of it. If this attempt fails for some reason I did find a few smaller health food stores online that claim to sell the un-diluted 35%.

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Re: I have finally found some diatoms

#11 Post by MichaelBrock » Mon Oct 01, 2018 12:46 am

The concentrating of the H2O2 is slow going but I think it's working. I ended up ordering some Potassium Dichromate so will go that route. I have asked around but our area apparently has few health food stores and so far I haven't found any that carry 35% or 30% H2O2. If the concentrating process ends up failing I'll give the sulfuric acid route a try (unlike H2O2, I can buy it in grocery stores).

After letting the sample settle in a graduated cylinder for a few hours I drew off some supernatant and it still had diatoms in it. I let it sit overnight, drew half of the supernatant and it still had diatoms in it. These things are precious to me (although I would be willing to drive the 1.5 hours to collect from the same place again; it was a good restaurant) so I drew off most of the supernatant and centrifuged it for 1/2 hour at 400rpm. That sample has diatoms in it, but not as many as I hoped/feared. I probably just need to learn to accept loses. I did a quick scan and found this. I have no idea what I'm looking at:
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Hobbyst46
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Re: I have finally found some diatoms

#12 Post by Hobbyst46 » Mon Oct 01, 2018 9:12 am

MichaelBrock wrote: ...I'll give the sulfuric acid route a try (unlike H2O2, I can buy it in grocery stores)
This stuff is fairly dangerous, I would take all precautions.
...I drew off some supernatant and it still had diatoms in it...
Small diatoms, say 10microns or less, will often remain in the supernatant. Filtration through a 13micron mesh cloth (cheaply available from AliExpress) will retain the small diatoms, but it will also retain other small unwanted stuff (silt etc) as well, and take ages, so not recommended.
I probably just need to learn to accept loses
Rather - enjoy the profit, those larger nice diatoms that are waiting within the precipitate!
Good luck with your advance!
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Re: I have finally found some diatoms

#13 Post by MichaelBrock » Tue Oct 16, 2018 5:04 pm

I am thoroughly enjoying searching through these slides. I have to remind myself that things I find will "be there later". I stumbled upon this guy during my lunch break. I'm reading up on the identification process. Hopefully I'll be able to identify some of these before too long (if for no other reason than I have a better way to name the picture files)
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Re: I have finally found some diatoms

#14 Post by 75RR » Tue Oct 16, 2018 6:16 pm

Nice catch! Is the black circle the edge of a bubble or part of the diatom?
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MichaelBrock
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Re: I have finally found some diatoms

#15 Post by MichaelBrock » Tue Oct 16, 2018 7:02 pm

75RR wrote:Nice catch! Is the black circle the edge of a bubble or part of the diatom?
A good question. The ring is in all images of the stack and I just assumed that it was just an area of higher density. I had not though about it previously but t would make sense that air could get trapped under the valve. That could very well be what it is. I'll have to look to see if I can find another of these.

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