When diatoms die, where does the silicates go?

[Miami Reef]

Where does the silicates go when a diatom bloom goes away? Isn’t it supposed to just leech back out from the dying diatoms?

It doesn’t make sense to me how a diatom bloom just stops. I think the most logical scenario is that the diatoms grow with enough silicates, then they die back from a limiting nutrient, and then leech back the silicates, then another diatom bloom should occur from the excess silicates.

 

[Miami Reef]

Let’s say I have a tank with high silicates (no livestock)

The diatoms grow and consume the silicate, then they deplete the silicates and die off. Won’t the diatoms release the silicates back into the water, resulting in a future diatom bloom?

Is that why we do water changes to remove the silicates in the water column as the diatoms die off? Or will using filter socks and skimming remove the dying diatoms which removes the silicates from the system?

But back to my original example, if a 10 gallon silicate heavy tank has a diatom bloom with no interventions, will there constantly be a boom/bust happening? Assuming no phosphates/silicates are being added/removed. The diatoms grow, soak up the nutrients, then die and releases them, then grow and absorb them…indefinitely…

Is this how it happens in a lab setting?

@Randy Holmes-Farley @Dan_P @taricha @ScottB

 

[fishmonkey]

Let’s say I have a tank with high silicates (no livestock)

The diatoms grow and consume the silicate, then they deplete the silicates and die off. Won’t the diatoms release the silicates back into the water, resulting in a future diatom bloom?

Is that why we do water changes to remove the silicates in the water column as the diatoms die off? Or will using filter socks and skimming remove the dying diatoms which removes the silicates from the system?

But back to my original example, if a 10 gallon silicate heavy tank has a diatom bloom with no interventions, will there constantly be a boom/bust happening? Assuming no phosphates/silicates are being added/removed. The diatoms grow, soak up the nutrients, then die and releases them, then grow and absorb them…indefinitely…

Is this how it happens in a lab setting?

@Randy Holmes-Farley @Dan_P @taricha @ScottB

That’s a good question. I’m not sure. I assume there is some chemical change going on there.

But if you suck up all the diatoms with a pump while doing a water change then technically most of that stuff would be gone.

 

[Sean Clark]

I presume the silicates would just go back into the water. Watching to see what others with more knowledge say.

 

[J1a]

Diatoms are preyed upon by copepods, corals etc. They are also easily skimmed out if they remain in the water column instead of remaining on rocks.

As long as some of these mechanism is working, diatoms can be removed, and scilicate, too.

 

[EeyoreIsMySpiritAnimal]

To the great sandcastle in the sky?

(Sorry, I've got no idea!)

 

[Rene2322]

Silicates seems to be used by many other organisms, like mollusks, sponges, but also by algae.
https://reefs.com/magazine/silica-in-reef-aquariums/

 

[dxEDGUFy]

Into my GFO

 

[mcgullen]

Hi.

Diatoms catalystically precipitate silicates into silica, or hydrolyzed silicon dioxide (very similar to glass), a rather non-reactive and water insoluble subatance suitable as diatoms' protective shells.

When diatoms die, their glass shells collapse into fragments called frustules. No silicate will be “released back" to the surrounding water because frustules are still silica. Put simply, diatoms' catalystic precipitation of silicates into silica is oneway.

In aquaria, these frustules can get into the water when diatom-eating animals poop or when dead diatoms are scraped off. They can cause a slight, white haze in water, but won't set off another diatom bloom in and of themselves. They can be effectively removed by activated carbon or by fine filter socks capable of intercepting 1μm particles.

In nature, these frustules collect at the bottom of the ocean over millions of years to form diatomite deposits, commonly known as diatomanous earth. Diatomanous earth as formed by these frustules have numerous microscopic holes, making them ideal mechanical filters.

You can get more information at https://diatoms.org/news/what-is-diatomaceous-earth or by google diatomanous earth.

 

[Dennis Cartier]

I would expect that the silicate is bound up in the skeleton and exoskeleton of the diatom and would remain inert. This would line up with the boom and bust cycles of a diatom bloom where they rapidly consume all the excess silicate from the water column and then fade away.

I am uncertain if silicate can unbind and release like phosphate can. My guy says no, not without bacterial or chemical assistance (low pH).

 

[fishmonkey]

Hi.

Diatoms catalystically precipitate silicates into silica, or hydrolyzed silicon dioxide (very similar to glass), a rather non-reactive and water insoluble subatance suitable as diatoms' protective shells.

When diatoms die, their glass shells collapse into fragments called frustules. No silicate will be “released back" to the surrounding water because frustules are still silica. Put simply, diatoms' catalytic precipitation of silicates into silica is one-way.

In aquaria, these frustules can get into the water when diatom-eating animals poop or when dead diatoms are scraped off. They can cause a slight, white haze in water, but won't won't set off another diatom bloom in and of itself. They can be effectively removed by activated carbon, by fine filter socks capable of intercepting 1μm particles.

In nature, these frustules collect at the bottom of the ocean over millions of years to form diatomite deposits, commonly known as diatomanous earth. Diatomanous earth as formed by these frustules have numerous microscopic holes, making them ideal mechanical filters.

You can get more information at https://diatoms.org/news/what-is-diatomaceous-earth or by google diatomanous earth.

Wow that’s interesting

 

[Miami Reef]

Hi.

Diatoms catalystically precipitate silicates into silica, or hydrolyzed silicon dioxide (very similar to glass), a rather non-reactive and water insoluble subatance suitable as diatoms' protective shells.

When diatoms die, their glass shells collapse into fragments called frustules. No silicate will be “released back" to the surrounding water because frustules are still silica. Put simply, diatoms' catalystic precipitation of silicates into silica is oneway.

In aquaria, these frustules can get into the water when diatom-eating animals poop or when dead diatoms are scraped off. They can cause a slight, white haze in water, but won't won't set off another diatom bloom in and of themselves. They can be effectively removed by activated carbon or by fine filter socks capable of intercepting 1μm particles.

In nature, these frustules collect at the bottom of the ocean over millions of years to form diatomite deposits, commonly known as diatomanous earth. Diatomanous earth as formed by these frustules have numerous microscopic holes, making them ideal mechanical filters.

You can get more information at https://diatoms.org/news/what-is-diatomaceous-earth or by google diatomanous earth.

Genius! Thank you so much! This theory makes a lot of logical sense to me! :)

 

[Randy Holmes-Farley Verified Community Expert]

Most will accumulate on the bottom or be exported, but, the silica in diatoms can slowly dissolve. It is not as slow to dissolve as quartz.

https://en.wikipedia.org/wiki/Main_Page
"Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor."

Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor.[
"Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians."

"In the deep ocean, another 26.2 Tmol Si Year−1 is dissolved before being deposited to the sediments as opal silica.[11] At the sediment water interface, over 90% of the silica is recycle"

 

[Roatan Reef]

That’s a good question. I’m not sure. I assume there is some chemical change going on there.

But if you suck up all the diatoms with a pump while doing a water change then technically most of that stuff would be gone.

That has been my experience as well...doing a water change with RODI Water and vacuuming up as much as you can during said water changes, your Diatoms will naturally die out, and you will be on your way to a happy and clear tank!

 

[taricha]

Diatoms can sink into deep sediment and remain alive for really long time too. Resting stage can be measured in months or years...

source

This paper goes into depth about the nutrient games they play to prep for long time of burial in the dark.
"A considerable fraction of the settled diatoms survive for months to decades as vegetative or resting cells in dark, anoxic sediment layers, in which neither photosynthesis nor aerobic respiration can occur (8–10). Benthic diatoms experience shifts to dark, anoxic conditions due to vertical migration behavior in the sediment (11) and burial by bioturbating animals (12)."

 

[Landia]

Hey everyone, this'll be my first post and wanted to resurrect this one.

Reading this thread and the links made me come up with some tangential questions. Please elucidate me if off track.

Here's my first volley, So do the diatom "skeletons" dissolve in the reef or remain in an inert state?

Google led me to Encyclopedia Britannica. I don't have a background in biochem but even this layman article was a bit above me at some parts and raises more questions.

https://www.britannica.com/science/biogenic-ooze
Can this quote below mean in a tank, the silicious "skeletons" can end up in the sand bed? Obviously the article is talking on a much more macro level.

"Siliceous oozes are more reliable indicators of high productivity than carbonate oozes. This is because silica dissolves quickly in surface waters and carbonate dissolves in deep water; hence, high surface productivity is required to supply siliceous skeletons to the ocean floor."

Per quote below, I guess diatom "micro skeleton pools" or oozes occured in artic areas? Do diatom skeletons dissolve in reef tank temperatures?

"The siliceous oozes exist only where the rate of deposition of diatoms or radiolarians is greater than the rate at which their silica content is dissolved in the deep waters; thus the diatom oozes are confined to belts in the North Pacific and Antarctic, and the radiolarian oozes are found only under the eastern part of the North Pacific."

 

[Randy Holmes-Farley Verified Community Expert]

Hey everyone, this'll be my first post and wanted to resurrect this one.

Reading this thread and the links made me come up with some tangential questions. Please elucidate me if off track.

Here's my first volley, So do the diatom "skeletons" dissolve in the reef or remain in an inert state?

Google led me to Encyclopedia Britannica. I don't have a background in biochem but even this layman article was a bit above me at some parts and raises more questions.

https://www.britannica.com/science/biogenic-ooze
Can this quote below mean in a tank, the silicious "skeletons" can end up in the sand bed? Obviously the article is talking on a much more macro level.

"Siliceous oozes are more reliable indicators of high productivity than carbonate oozes. This is because silica dissolves quickly in surface waters and carbonate dissolves in deep water; hence, high surface productivity is required to supply siliceous skeletons to the ocean floor."

Per quote below, I guess diatom "micro skeleton pools" or oozes occured in artic areas? Do diatom skeletons dissolve in reef tank temperatures?

"The siliceous oozes exist only where the rate of deposition of diatoms or radiolarians is greater than the rate at which their silica content is dissolved in the deep waters; thus the diatom oozes are confined to belts in the North Pacific and Antarctic, and the radiolarian oozes are found only under the eastern part of the North Pacific."

Welcome to REEF2REEF!

As folks have noted, the silica in diatoms can very slowly dissolve, but the emphasis is on slow and for most reef tank purposes, folks should assume most of the silicate is taken out of circulation and it stays out. That can be by export of material (skimmers take out a lot of diatom materials), by incorporation into other organisms (snails, spi germs, other diatoms, etc)

The “quickly” term in the article you posted is seemingly referring to geologic time scales, not days.

Articles aside, many folks including me have determined that silica consumption is mostly a one way trip, and I dosed weekly for years to keep levels up.

 

[roggy23]

That has been my experience as well...doing a water change with RODI Water and vacuuming up as much as you can during said water changes, your Diatoms will naturally die out, and you will be on your way to a happy and clear tank!

So vacuuming during water changes will speed up the ugly stage?

 

[Randy Holmes-Farley Verified Community Expert]

So vacuuming during water changes will speed up the ugly stage?

I would not assuming that diatom bodies are dissolving substantially in the time frame of a few weeks.