# The invasion of the diatoms!



## Tentacles (Jun 25, 2006)

My NPT 2ftx2ft has been going for 2 years without any problems, it is full of shrimp, snails, little fish, duck weed and slower growing plants, but now I can't see in anymore because diatoms have colonised the glass! The only bit of glass underwater they haven't colonised is the first 10cm next to the substrate.

They are brown diatoms and impossible to physically remove by scraping.

I suspect the snail populations have raised the calcium levels. But of course, I don't test the water so I have no information to back that up and it is a closed system only topped up by fairly empty soft water. So how would snails growing and dying add extra calcium to the water?

Anyway, when your tank is 2ft tall and you're considering catching 400 shrimp in amongst loads of plants in a tank you can't actually see into or reach the bottom of and breaking down the tank to soak it in chlorine... you know things are serious.

I know diatoms are little animals so light isn't a factor like it is for algae. Water changes may help but it hasn't seemed to, and it doesn't help the poor plants out much.

Has anyone else had diatom invasion of glass surfaces before and solved it?


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## Tex Gal (Nov 1, 2007)

Diatoms come off easily, but then resettle. When I had them (new tank), they got on everything not just the glass. It sounds like you have something else going on. The description below come from the sight below. Check it out. Are you sure they are diatoms?

DIATOM ALGAE
Description Forms in brown patches on the glass, substrate and plants.
Cause Usually found in newly setup tanks due to silicates and ammonia as the filter and substrate have yet to mature.
Removal Can be vacuumed out or wiped of the glass with a soft cloth. Usually disappears after a few weeks when the tank has matured. Otocinclus will eat it.

http://www.theplantedtank.co.uk/algae.htm


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## tug (Jul 23, 2009)

Diatoms are that muck that covers plant leaves and hardscape items. Maybe Green Dust Algae (GDA) or Green Spot (GSA). I have found that GSA, (Choleochaete orbicularis) and PO4 don't play well together. If what you have is GSA you might have low levels of PO4 :tape2: Brown algae, GSA and other algae can be found at Guitarfish.org http://www.guitarfish.org/algae#greenspot


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## Red_Rose (Mar 18, 2007)

When I had set up my first 10g for my betta, the diatoms were so thick on the glass that even scraping it off was a struggle. What I did to clear it up and keep it that way was by adding two Zebra Nerites to the tank. They love diatoms and in no time, the glass was spotless.


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## Tentacles (Jun 25, 2006)

Diatoms are little hard-shelled beasties... I think they're also called golden brown diatoms. I'm not sure if they're my beastie but some descriptions of them seem to fit. Like this one:
http://www.skepticalaquarist.com/docs/algae/diatoms.shtml
The description of an incrustation fits.

They are different to what is described as brown algae and those strange pictures of dusty beasties on plants that are described as brown diatoms as at guitarfish. I don't see anything dusty about it.

What I have resembles hard-shelled little beasties layered on the glass, not dusty anythings. It is also on the older leaves of the slower growing plants but mostly it loves the glass.

A razor blade can scrape furrows in them, and I've used plastic pot scrubbers on them with little effect. Soft cloth is not an option. It is not a film, it is an incrustation of something brown and it doesn't bother with patchy bits it's taking all the glass from the waterline down to about two inches off the substrate.

This is an old tank, it doesn't usually suffer algae blooms or sudden changes. A build up of something has caused conditions to be perfect for this brown stuff and the shrimps especially are loving it. They can now run up and down the previously slippery walls and they've had a major population explosion.


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## Tentacles (Jun 25, 2006)

Red_Rose said:


> When I had set up my first 10g for my betta, the diatoms were so thick on the glass that even scraping it off was a struggle. What I did to clear it up and keep it that way was by adding two Zebra Nerites to the tank. They love diatoms and in no time, the glass was spotless.


Do you think your problem was similar to mine? Were you physically unable to scrape the beasties off? I'm having trouble imagining any fish can deal with it... and I have a lot of smaller snails already, but if they can, it would certainly be easier than breaking down the whole tank. It's just too enormous.


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## Tentacles (Jun 25, 2006)

tug said:


> Diatoms are that muck that covers plant leaves and hardscape items. Maybe Green Dust Algae (GDA) or Green Spot (GSA). I have found that GSA, (Choleochaete orbicularis) and PO4 don't play well together. If what you have is GSA you might have low levels of PO4 :tape2: Brown algae, GSA and other algae can be found at Guitarfish.org http://www.guitarfish.org/algae#greenspot


Phosphates? I'm using extremely soft and empty water. I know it is really hard to change levels of anything in very soft water. I don't think I have a phosphate test in my test kit.

It does seem to behave like Green Spot Algae... apart from being brown, that is.

How would one proceed if one lacked phosphates?


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## tug (Jul 23, 2009)

I find when PO4 levels begin to bottom out I see more of whatever that stuff is. The plants (Dutch planted tank, maybe?) seam to store it, (i think) keeping a high amount on hand. A nfg reagent test showed a 3 ppm change from 2 to 5 and back to 2 ppm in 48 hours. Any, (KH2PO4) phosphate enriching the water stream anywhere from 2.9 - 4 ppm, seams to help. Find a dry, (KH2PO4) fertilizer. Less water, (you can add your own) and it's less money from out oyw.



> A Russian study suggested that high ratios of silica to phosphorus (as phosphate) encouraged the diatoms in the algae/cyanobacteria/diatom community, but that lower ratios of silica to phosphorus found planktonic green algae displacing diatoms.


Your beastie;
thanks by the way -
http://www.skepticalaquarist.com/docs/algae/diatoms.shtml If a study points to high ratios of silica to phosphorus; other silica, PO4 and Fe studies show algae are not limited by low levels of any of these. They don't need a lot! I would guess it, (PO4) bottoms out and the plants do suffer some and the algae, (whatever it is) comes back.

The problem with adding one element, is you do often see a change from one kind of algae/limiting element replaced by another type of algae/limiting factor. I began this fun without giving the substrate the attention I owed, due to time constraints. That's what Estimative Index (EI) addresses. I have included some links that explain more, I am but a scarecrow.

Green Glass Algae and PO4

The Estimative Index of Dosing, or No Need for Test Kits

The Estimative Index Non CO2 methods
Or, like I like to call it, EINPA. Sounds more like beer that way.

artyman:


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## Tentacles (Jun 25, 2006)

Thanks, Tug. Interesting reading. I'm sure lack of phosphates is part of the problem.


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## Tentacles (Jun 25, 2006)

I got my test kit out and it showed something interesting. A sudden increase in GH and KH.

Normally the water is empty and soft and these sit around 80 for GH and 40 for KH.
Now they are 160 for GH and 130 for KH! Something the wee beasties and the snails are doing, I suspect.

Ammonia and Nitrite were negligible and the pH was 7.2

Don't have a phosphate test.


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