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Anyone used the JBL SiO2 test?

orxe87

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Only if this is a high reading, and not an anomolous one :) Not proven yet.

Just tried to take a photospectrometer reading from the sample and failed - my kit just isn't set up for transmissive colours unfortunately. All I'll say again is that it is very different to the swatch - a pure deep sapphire blue. I'll hold off until I can get some RO and do a diluted test, hopefully this weekend.
 

jaypeecee

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...so a 'high' silicate test reading certainly doesn't mean diatoms are inevitable.
Hi @sparkyweasel

So true. And, I may have answered my own question concerning what diatoms eat. Silly me - they're photosynthetic creatures so they make their own food from a soup of elements, one of which has to be silicon. But, the $64,000 question is - where does that silicon come from?

JPC
 

dw1305

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Hi all,
But, what is certain is that diatoms must obtain silicon (Si) from somewhere.
They definitely get it from solution in the form of orthosilic acid. Apparently the exact mechanism, is fairly complex and has only been fully described recently.

Hildebrand, M et al (2018) "Understanding Diatom Cell Wall Silicification—Moving Forward" Front. Mar. Sci., 5 pp 125 says:
........ However, recent studies that monitor when components are made, and how they are transported to the silica deposition vesicle (SDV), indicate that investigation into the true dynamics of the process is possible. Real-time imaging and genetic manipulation offer the promise of elucidating the spatio-temporal dynamics of, and interactions between, components........Silicon dissolved in an aqueous solution at neutral pH is primarily in the form of silicic acid, Si(OH)4 (Iler, 1979). The solubility of a silicic acid solution is limited to around 2 mM, above that concentration silica (SiO2) begins to polymerize into polymers with a range of lengths, forming an amorphous solid (Iler, 1979; Kley et al., 2014)........ As a small, uncharged molecule, silicic acid can freely diffuse across membranes. Kinetic data indicate that, under environmentally relevant concentrations, diffusion can be the major mode of uptake (Thamatrakoln and Hildebrand, 2008). Under relatively low silicic acid concentrations, the silicon transporters (SITs) actively facilitate uptake.........
(from op)
so a 'high' silicate test reading certainly doesn't mean diatoms are inevitable.
This is definitely only for curiosity - no issue with diatoms, no reason to think that SiO2 is causing any negative effect in the tank.
That would definitely be where I'm coming from. Diatoms are pretty <"much universal in liquid water"> (including melt water pools on glaciers, soil water, wet moss etc.) so I'm not sure where it comes from is really helps, the diatoms are there, so all liquid water must have enough silicon to support frustule construction.
......Diatoms are found in all freshwater habitats, including standing and flowing waters, and planktonic and benthic habitats, and they can often dominate the microscopic flora. Because diatoms inhabit a broad array of habitats but many have specific habitat requirements, they have been used in freshwater environment assessment and to monitor long-term changes in ecological characteristics.......

cheers Darrel
 
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jaypeecee

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But, the $64,000 question is - where does that silicon come from?
Hi Everyone,

Well, the source of silicon is the tap/tank water - unless anyone can suggest an alternative/additional source. But, I've been digging into this somewhat deeper. It appears that there are three elements that are critical to the growth of diatoms, one being silicon. The other two are - not surprisingly, nitrogen and phosphorus.

"Phosphorus is seen as the nutrient that most likely to limit primary production in freshwaters"*.

"In many situations nitrogen may well be the limiting nutrient"*.

As most, if not all the research has been carried out on lakes and rivers, the classification of such waters typically ranges from oligotrophic to eutrophic. And, on this basis, the phosphorus concentration is from <0.015 to 0.055 mg/l (ppm). Converting this to phosphate figures (as measured by test kits), I make this a phosphate range from <0.05 to 0.17 mg/l (ppm).

Now some additional information:

"The ratio between Si and P, and the ratio between Si and N, determines which algae is (dominantly) present in the water. In natural waters, diatoms are often dominant in the spring (March-May). Their dominance is usually ended when all silicate is used and stored in the diatoms. When the diatom “bloom” collapses, it is often followed by the dominance of other (non-diatom) algae. The effects of an increased silicate concentration can be: - Shifts in algae species composition. Additional silicate will increase the Si/P and Si/N ratio in the water, thus creating conditions more favorable for diatoms; - Increased algae biomass. As mentioned, the development of diatoms in the spring is usually ended when silicate is depleted"**.

That's as far as I've got.

I'd like to make a personal request. If anyone is interested in trying to work together towards a team solution on this topic, then please do so. I'm no more qualified than anyone else to solve the diatom outbreak problem. But, wouldn't it be nice if we could collectively advance our knowledge of this topic?

* http://craticula.ncl.ac.uk/EADiatomKey/html/index.html (unfortunately, this website right now appears to be out of action :mad:)

** Water quality information - What are silicates and why are they in water? | APEC Water

JPC
 
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dw1305

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Hi all,
Well, the source of silicon is the tap/tank water - unless anyone can suggest an alternative/additional source.
I'd go further than that, it is any (and every) water source.

It is the combination of persistent skeleton, the <"ubiquity of diatoms"> and <"their huge diversity">, that makes them useful as a <"trophic index">. If they weren't so common they wouldn't be so useful.

cheers Darrel
 

jaypeecee

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I'll hold off until I can get some RO and do a diluted test, hopefully this weekend.
Hi @orxe87

That will be interesting.

BTW, I hope you didn't mind the detour as to the factors leading to diatom outbreaks. Slapped wrist for me!

JPC
 
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John q

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"The ratio between Si and P, and the ratio between Si and N, determines which algae is (dominantly) present in the water.
Hi jpc, always interesting to read up on these subjects but I must admit a lot of the reading I did went over my head.
I think the article you first mentioned was referencing this paper.

I also found this article interesting in regards to people that have hypothesised for the last century over various limiting factors on phytoplankton growth, only for these to be later disproved.
I've attached links to abstracts of the above articles and tried to add the full pdf files but not sure if I can upload these?

My understanding of the above articles for what it's worth makes me believe that if we are to create an environment that is beneficial to plant growth, then by default there will always be sufficient nutrition to feed diatoms and or algae.

Feel free to correct my understanding of the above.
 

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dw1305

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Hi all,
My understanding of the above articles for what it's worth makes me believe that if we are to create an environment that is beneficial to plant growth, then by default there will always be sufficient nutrition to feed diatoms and or algae.
I'd tend to agree with that. It is the "plants you want ("Plants")" and "plants you don't (Algae)" argument, for me <"the bottom line"> is that <"they are all plants">.

cheers Darrel
 

jaypeecee

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My understanding of the above articles for what it's worth makes me believe that if we are to create an environment that is beneficial to plant growth, then by default there will always be sufficient nutrition to feed diatoms and or algae.
Hi @John q

You may well be correct. But, what if we could take advantage of the fact that diatoms, algae and cyanobacteria all obtain their nutrients from the water column whereas many/most plants can obtain most nutrients from the sediment/substrate? I say 'most nutrients' in the case of plants because they typically obtain carbon from CO2 injection or atmospheric CO2.

JPC
 

sparkyweasel

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But, what if we could take advantage of the fact that diatoms, algae and cyanobacteria all obtain their nutrients from the water column whereas many/most plants can obtain most nutrients from the sediment/substrate?
That's something interesting to think about.
But won't the nutrients in the substrate dissolve into the water? Although the 'wanted plants' might get the lion's share due to having their roots right in the substrate, I think there will always be some leaching into the water column, and we know that the 'unwanted plants' don't seem to need a lot of nutrients to survive.
 

dw1305

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Hi all,
But won't the nutrients in the substrate dissolve into the water? Although the 'wanted plants' might get the lion's share due to having their roots right in the substrate, I think there will always be some leaching into the water column
I think that is right. Plants can only take up nutrient as ions from solution and there must always be some interchange between substrate and water column.

The easiest "nutrient" to remove from the water column is light, if you don't get above LCP then you don't have any algae, but obviously that doesn't help us (or any-one else to be honest). After that my guess would be the next <"easiest is phosphorus (P)"> as <"PO4--- ions">, because of the wide range of <"insoluble phosphate compounds">, particularly in alkaline conditions.

It is likely to be a while before plants <"show phosphate deficiency">, even if you totally remove all PO4--- ions.

cheers Darrel
 

orxe87

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Managed to get some RO today (a whopping 14p a litre) so I've just been playing with RO dilution of the sample. I needed to take it down to 20% sample strength to get into the valid range for the test, so after multiplying back up that gave about 8.5mg/L Si02 in my tap water. (Control sample of 100% RO was 0mg/L).

So, simply overrange on the test, then.

I still maintain that the '>6' top colour swatch on the test chart bears no resemblance whatsoever to the colour of the sample... :)
 

jaypeecee

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Although the 'wanted plants' might get the lion's share due to having their roots right in the substrate, I think there will always be some leaching into the water column, and we know that the 'unwanted plants' don't seem to need a lot of nutrients to survive.
Hi @sparkyweasel

Thanks for the feedback.

I agree with what you say 100%. But, we have a choice - take on the challenge or give up at the first hurdle. I'm not for giving up yet. I want to find out what's possible first. It's much more rewarding making improvements - no matter how small. And it's exciting making new discoveries. Darrel (@dw1305) has suggested taking a look at phosphorus/phosphate. Could this be a useful starting point? I also seem to recall that Diana Walstad is not in favour of adding iron to the water column - I'll check this.

JPC
 

jaypeecee

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I also seem to recall that Diana Walstad is not in favour of adding iron to the water column - I'll check this.
Hi Folks,

In Ecology of the Planted Aquarium, Diana Walstad comments that "In my opinion, the substrate - not the water - is the best place to provide plants with iron".

JPC
 

sparkyweasel

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Hi @jaypeecee , I know you won't give up in your quest. :)
On the subject of iron in the substrate, that was very 'fashionable' for want of a better word some years ago. Before the trend for fancy substrate, a layer of iron-rich material, such as laterite clay was popular, under inert sand or gravel.
 

jaypeecee

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Before the trend for fancy substrate, a layer of iron-rich material, such as laterite clay was popular, under inert sand or gravel.
Hi @sparkyweasel

Many years ago, I used laterite myself but I'd have to try to find any notes I made at the time to see whether or not it was beneficial. I know that @dw1305 isn't a fan of laterite - comparing it to crushed house bricks or something like that. Darrel will correct me if I've got the wrong end of the stick.

JPC
 

dw1305

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JanisF

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I've used SiO2 from JBL. I bought it to test the water in our office tank and tap. It came back as >6pmm
I then asked for tap water samples to be taken to an independent lab for testing and as a matter of fact today I received the test results - our tap water SiO2 level at the time of testing was 8.5ppm.
So I guess the test was not wrong. Also I've used it at home on my RODI water and it came back as <0.1ppm.
 

jaypeecee

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After that my guess would be the next <"easiest is phosphorus (P)"> as <"PO4--- ions">, because of the wide range of <"insoluble phosphate compounds">, particularly in alkaline conditions.

It is likely to be a while before plants <"show phosphate deficiency">, even if you totally remove all PO4--- ions.
Hi @dw1305

You may recall that I recently had a phosphate deficiency in one of my tanks. It manifested as Frogbit turning very pale and dying off but it took me a few days to recognize that phosphate was very low. I was testing the tank water one day - only to find that phosphate was <0.02 mg/l (ppm). In the water sample that I recently had analyzed using ICP-MS, phosphorus measured 19 micrograms/litre. I make this 0.06 mg/l (ppm) phosphate in round numbers. Unfortunately, the Frogbit died off but the Java Ferns are thriving on this level of phosphate.

Out of interest, why does it take "a while" before plants show a phosphate deficiency? Is this because aquarium plants can store a reserve of phosphate?

JPC
 
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