# Sodium silicates in tap



## Maxplantinstitute (10 Feb 2022)

I just found out my watercompany adds sodium silicates (Na2O*nSiO2) or equivalent to our tapwater to prevent corrosion.

And when I read about this process I found out it the silicates also binds with Fe, Mn and other elements.

So I wonder what implications this might have for my aquarium? I used a JBL silicate test (SiO2) and my tapwater levels was through the roof. I had to dilute the sample 50/50 to even got on the scale of the color score chart(I think, color comparison is not always easy).

I have always had diatoms in my tank and I know the general consensus is that silicates does not cause diatoms, but it doesnt help either.

Is the addisjon of silicates to my tapwater something I should take into consideration and maybe get a RO unit, or is this unproblematic for planted tanks and I should not worry about this?

Can someone please help ease my mind in this matter?


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## swyftfeet (10 Feb 2022)

Maxplantinstitute said:


> I just found out my watercompany adds sodium silicates (Na2O*nSiO2) or equivalent to our tapwater to prevent corrosion.
> 
> And when I read about this process I found out it the silicates also binds with Fe, Mn and other elements.
> 
> ...


From what Ive read diatoms can only reproduce when there is enough silica in the water to do.

I had a diatom outbreak when towards the end of a tanks "cycle" or maturation. 
Coincidentally it occured after  we went on vacation for 4 days and I added an auto feeder, which I couldn't quite dial in well.  It either way over fed or didn't feed enough.  I did my best by gerry rigging the opening with some tape, but even then it was in my estimation overfeeding somewhat on some feeds and underfeeding on others.

Anyway. about a week after we got back  Diatoms  went absolutely bananas for about 3 weeks.  The tank had brown on everything everywhere, glass plants etc.

I bought 2 nerite snails (15g tank)  and they did well at cleaning it up, also I did some pretty significant gravel vacuuming and its back under control, almost pristine.

I dont think silica is the trigger for diatoms, I think it is water quality, but the silica is the primary building block required for diatoms to reproduce.


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## swyftfeet (10 Feb 2022)

Seems a group in Oregon have determined that excess ammonium can trigger a sex change in diatoms  Article
So again it could point back to water quality triggering a bloom and the silica available being the building blocks.


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## Maxplantinstitute (11 Feb 2022)

From wikipedia:

Water treatment[edit]​Sodium silicate is used as an alum coagulant and an iron flocculant in wastewater treatment plants. Sodium silicate binds to colloidal molecules, creating larger aggregates that sink to the bottom of the water column. The microscopic negatively charged particles suspended in water interact with sodium silicate. Their electrical double layer collapses due to the increase of ionic strength caused by the addition of sodium silicate (doubly negatively charged anion accompanied by two sodium cations) and they subsequently aggregate. This process is called coagulation

Question: what implications might this sodium silicate treatment of my tap water have for my plated aquarium?

Can Sodium silicate affect the levels of Fe, Mn and other vital plant nutrient elements I add, if I use unfiltered tap water? And would a RO type filter effectively remove this Sodium silicate and resolve this problem (if this is a problem at all)?


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## dw1305 (11 Feb 2022)

H all,


Maxplantinstitute said:


> Can Sodium silicate affect the levels of Fe, Mn and other vital plant nutrient elements I add, if I use unfiltered tap water?


Potentially it can form insoluble compounds with all the multivalent cations (so basically everything except sodium (Na) and potassium (K)).


Maxplantinstitute said:


> So I wonder what implications this might have for my aquarium?


<"I'm not sure it has any">.  The added sodium silicate is soluble and some of that silicate will end up as "orthosilicic acids" and these are the silicon containing compounds that Diatoms us to build their frustules, but Diatoms are incredibly efficient at this, and you would have to <"remove all the orthosilic acid to stop them growing">.

You could try adding <"some Hornwort"> (_Ceratophyllum demersum_).

cheers Darrel


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## MichaelJ (11 Feb 2022)

Maxplantinstitute said:


> So I wonder what implications this might have for my aquarium? I used a JBL silicate test (SiO2) and my tapwater levels was through the roof. I had to dilute the sample 50/50 to even got on the scale of the color score chart(I think, color comparison is not always easy).
> Is the addisjon of silicates to my tapwater something I should take into consideration and maybe get a RO unit, or is this unproblematic for planted tanks and I should not worry about this?


Hi @Maxplantinstitute  How is your tank doing in general?   If you really want to deal with the high silicate levels you  have to go pure RO (or rainwater) and remineralize from there.

Cheers,
Michael


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## X3NiTH (11 Feb 2022)

As long as the trace metals you are adding are chelated and the pH of the tank when the traces are dosed is in range for the chelate then the trace metals will be bound and plant available, if the pH is out of range for the chelate metal bond (mainly for Fe) then any unchelated metals are free to react and form Silicate compounds. The diagram below shows the condition states for free Iron precipitation with silicates.





The graph is taken from this paper -

Iron (III)-silica interactions in aqueous solution: Insights from X-ray absorption fine structure spectroscopy

So as you can see Silicate is only really a problem in low pH environments.


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## jaypeecee (11 Feb 2022)

Maxplantinstitute said:


> I have always had diatoms in my tank and I know the general consensus is that silicates does not cause diatoms, but it doesnt help either.


Hi @Maxplantinstitute 

The use of this expression "does not cause" is often used in the aquatics hobby, isn't it? But, silicate _contributes_ to growth of diatoms. And what effect is the sodium having on your tank water? If you take a look at your water company's annual report, it should include sodium (Na). FYI, one of my annual reports states a minimum of 19.00 mg/l, a mean of 26.06 mg/l and a maximum of 37.60 mg/l of sodium.

You may want to consider rainwater and/or re-mineralized RODI* water.

* RODI is Reverse Osmosis + Deionized

JPC


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## Maxplantinstitute (14 Feb 2022)

MichaelJ said:


> Hi @Maxplantinstitute  How is your tank doing in general?   If you really want to deal with the high silicate levels you  have to go pure RO (or rainwater) and remineralize from there.
> 
> Cheers,
> Michael


after the first regular start up issues the diatomes never went away. I have had 3 years of persistent diatome growth. Not overwhelming but annoying.
 All the other issues have come and gone or been resolved and returned but brown algea has proved to be  stubborn.


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## Maxplantinstitute (14 Feb 2022)

jaypeecee said:


> Hi @Maxplantinstitute
> 
> The use of this expression "does not cause" is often used in the aquatics hobby, isn't it? But, silicate _contributes_ to growth of diatoms. And what effect is the sodium having on your tank water? If you take a look at your water company's annual report, it should include sodium (Na). FYI, one of my annual reports states a minimum of 19.00 mg/l, a mean of 26.06 mg/l and a maximum of 37.60 mg/l of sodium.
> 
> ...


The last rapport i got was from 2019 and it listed 9,3mg/l Na. 
i dont know if this is hi or low in a planted aquarium context. 
100l of RO water a week? hmmm i am already too far down this rabbithole. I dont really fell like spending that much  on a RO setup. I can try rainwater in summertime thou.


dw1305 said:


> H all,
> 
> Potentially it can form insoluble compounds with all the multivalent cations (so basically everything except sodium (Na) and potassium (K)).
> 
> ...


Hornwort is on my "to do" list, definitely.


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## ceg4048 (14 Feb 2022)

Maxplantinstitute said:


> Is the addisjon of silicates to my tapwater something I should take into consideration and maybe get a RO unit, or is this unproblematic for planted tanks and I should not worry about this?


Hello,
           No, you should not. Instead, you should worry about the possibility that your lighting is too high, or a myriad of other issues that trigger algal blooms.

Cheers,


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