# Sodium and plants



## GlassWalker (19 Oct 2014)

I have a feeling this might be a "how long is a piece of string" type question, but how much sodium do you need before there are adverse effects on plants? I presume different plants would have different tolerances e.g. marine plants might like a lot of it! But here I'm of course more interested in typical tropical freshwater aquarium plants.

In case you're wondering why I'm asking this, my main tank is a heavily stocked with fish and that chews through KH like it is going out of fashion. On top of water changes, I intend to start dosing to help keep it from getting too low.

I did a rough calculation earlier. Since I have dosing bottles that makes it easy for me to apply. They're 500ml, and by my calculations I can use 91g of potassium bicarbonate per 500ml to give a solution, which at 20ml in 100L would give 1 dKH and 14mg/l potassium. My water is already high in potassium to start with, and I'm dosing EI on top of that... so I'm half debating if I should use sodium bicarbonate. That also has a minor plus in that I already have a mix of that prepared for my marine tanks. I guess I'm more worried about the presence of sodium than I am about a possible excess of potassium. If I used sodium bicarbonate, I'd be adding 8.3mg/l of sodium per dKH.


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## ceg4048 (20 Oct 2014)

There are no negative effects of high potassium.
I routinely dose Potassium at values exceeding 100ppm K+ so it's a pointless waste of time worrying about K+ toxicity.
Here is a tank dosed at approximately 130ppm K+
If people want to worry then they always choose to worry about CO2 above everything else.





On the other hand, it should not be too much of a problem using Sodium Bicarbonate to adjust alkalinity, but it depends on the plants. The range is vast. Florida lakes, for example have Na++ concentrations from about 10ppm inland  to over 1000ppm in areas near the coast, so there is some adaptability. Other plants originating from areas where there is no coast or saline source may not be as adaptable. Generally it's best to avoid using water from a water softener which uses salt as these will have very high Sodium concentrations.

Cheers,


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## Martin in Holland (20 Oct 2014)

Nice picture Clive. Would be even better if you would have cleaned the glass on the outside first...LOL (sorry mate, couldn't resist)


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## Bhu (20 Oct 2014)

GlassWalker said:


> In case you're wondering why I'm asking this, my main tank is a heavily stocked with fish and that chews through KH like it is going out of fashion.



Hi All

Can someone please explain what the OP means by this statement? I'm knew to water chemistry and planted tanks and do have a really soft water due to using RO water. Can this cause problems if the dKH is too low? 

Best wishes

Bhu


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## GlassWalker (20 Oct 2014)

Thanks for the reassurances on potassium. I'll stick to the plan of using potassium bicarbonate then as it is likely less risky than using sodium.

On the KH consumption, for now, pretend there are no plants in tank. We only have fish and a biofilter provided by an internal or external filter populated with bacteria (or whatever it is the latest research says they are). When those bacteria oxidise ammonia through to nitrate, they also consume KH in the process. If there aren't many fish, then normal water changes alone are generally ok to restore that and you don't have to worry about it. In the case of one of my tanks, I'm running soft water (remineralised RO) and a LOT of fish, pushing the upper limits of what's considered a good amount. They're also very hungry fish and take a lot of feeding. I haven't taken close measurements but I do note my KH value drops <1.0 by the time a water change comes around. I'm thinking I want a bit more buffer than that which can be provided by extra dosing and/or altering the balance of the remineralisation salts.

I don't know if plants affect the above process significantly. They will likely consume some of the ammonia before the filters get to it, but I don't know if they similarly consume KH in any significant amount. At least, I don't recall ever hearing of using (bi)carbonates as a fertiliser.


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## ian_m (20 Oct 2014)

Quote from:
http://www.skepticalaquarist.com/water-softening

"Sodium is undesirable in a freshwater aquarium..."

Which is why I can't use my house hot water as it has been softened by ion exchange.


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## dw1305 (20 Oct 2014)

Hi all,





GlassWalker said:


> I'm running soft water (remineralised RO) and a LOT of fish, pushing the upper limits of what's considered a good amount. They're also very hungry fish and take a lot of feeding. I haven't taken close measurements but I do note my KH value drops <1.0 by the time a water change comes around. I'm thinking I want a bit more buffer than that which can be provided by extra dosing and/or altering the balance of the remineralisation salts.


 You could just add some of your potassium as KHCO3 if you are worried about the dKH falling. Once they are in solution every K+ ions is the same, it doesn't matter what compound they came from. 





ian_m said:


> "Sodium is undesirable in a freshwater aquarium..."


 Pretty much, there is actually similar reserves of sodium and potassium on the earth, but because plants don't have a sodium requirement the sea is salt with NaCl (the Cl has accumulated for similar reasons).

cheers Darrel


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## GlassWalker (20 Oct 2014)

My original concern other than sodium was possible buildup of potassium. As already noted, this doesn't sound like an problem at any level I'm likely to come across. I did wonder if there was a way to reduce the proportion of potassium in EI, but if there is I can't think of an easy way. In other words, what else would I swap it with? I'll leave it there.


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## dw1305 (21 Oct 2014)

Hi all, 





GlassWalker said:


> I did wonder if there was a way to reduce the proportion of potassium in EI, but if there is I can't think of an easy way. In other words, what else would I swap it with? I'll leave it there.


 If you want to add more dKH just add some KHCO3, it will raise conductivity and dKH, but other than that it won't have any adverse effects.

It is the same with anion exchange resins, you can always substitute KCl for NaCl when you re-charge them, the cation doesn't matter.

A lot of commercial re-mineralising salt mixes have NaCl or NaHCO3 in them as a "filler", because it is the cheapest option, and all the talk about "_osmotic pressure_" etc.  is just "_smoke and mirrors_".

Swapping compounds in EI is probably more a nitrogen problem than a potassium one.

Potassium nitrate (KNO3) supplies both your K and N.  Any other potassium compound could be used for the K, and a compound like KCl would be widely available.

Suitable nitrates would be Mg(NO3)2.6H2O or Ca(NO3)2.4H2O, but they don't offer any advantage of KNO3.  Details are in the <"How much calcium nitrate ....">  & <"Spezial N - Nitrogen fertilizer"> threads.

cheers Darrel


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## jaypeecee (30 Jul 2018)

ceg4048 said:


> On the other hand, it should not be too much of a problem using Sodium Bicarbonate to adjust alkalinity, but it depends on the plants. The range is vast. Florida lakes, for example have Na++ concentrations from about 10ppm inland  to over 1000ppm in areas near the coast, so there is some adaptability. Other plants originating from areas where there is no coast or saline source may not be as adaptable.


Would you care to expand on this? Has anyone compiled a list of plants showing their relative (in)tolerance to Na++ and the actual corresponding Na++ numeric concentrations in ppm? How well (or not) would Echinodorus varieties, for example, cope with sodium ions? I ask because I'm concerned that the remineralizing RO salts that I use can raise the Na++ concentration to 30ppm. I have no way of knowing before planting if that's good or bad.

Thanks in advance.


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## AverageWhiteBloke (30 Jul 2018)

I think I would be more concerned about the effects of sodium on fish especially Amazonian species than I would about Potassium for plants. In the EI article on UKAPS the recommendation for potassium is 30ppm per week. I knocked up a little chart just for my own use so whatever size tank I'm dosing I can quickly work out how many mils out of the same bottle should go into each tank obviously depending on the tank volume so I just have one EI macro mix bottle sitting about I can use on every tank.



 
As you can see from that, even at what is considered to be EI values of PO4 and KNO3, weekly you would be adding about 20ppm of potassium so you still have another 10ppm you could add via the potassium bicarbonate. Plants tend to get through a bit of potassium anyway. In my low tech tanks where I either don't dose kno3 or po4 because the lighting is so low and fish waste provides enough I tend to find that it's always the pot that is needed first. Soon as I add some potassium sulphate the plants perk up. Like Clive says though you could even be up from the 30ppm EI standard without worry, 5x that in Clives case  

Aquarium Plant Foods do Magnesium Nitrate which you could swap out for potassium nitrate in your EI mix and just carry on with the potassium carbonate which should lower the potassium levels a touch if it concerns you. Could you not just also bag up some chick grit in some tights or the various filter mesh bags you can buy and pop it in your filter canister? That should buffer up your KH without adding further sodium or potassium.


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## ceg4048 (8 Aug 2018)

jaypeecee said:


> Would you care to expand on this? Has anyone compiled a list of plants showing their relative (in)tolerance to Na++ and the actual corresponding Na++ numeric concentrations in ppm? How well (or not) would Echinodorus varieties, for example, cope with sodium ions? I ask because I'm concerned that the remineralizing RO salts that I use can raise the Na++ concentration to 30ppm. I have no way of knowing before planting if that's good or bad.
> 
> Thanks in advance.


No, sorry, I have not seen a list. Folks just accept that Sodium is not nice and simply avoid using it. Are you certain that your agent of choice uses Sodium? It would be very unusual. You haven't mentioned the brand but there are many products on the market that don't use Sodium.

In any case, I don't think 30ppm or the buildup due to water changes will be too much of a problem based  on some studies done (at least for those particular species), such as https://www.google.com/url?sa=t&rct...08223382.pdf&usg=AOvVaw1gM_fpSvV0HkxJW7scwpyH 
as well as https://www.jstor.org/stable/1351922?seq=1#page_scan_tab_contents
where the numbers reached into the thousands of ppm. Those species are fairly hardy though so it really isn't clear how to apply these values to the more sensitive species such as carpet plants and so forth.

Cheers,


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## jaypeecee (8 Aug 2018)

ceg4048 said:


> No, sorry, I have not seen a list. Folks just accept that Sodium is not nice and simply avoid using it. Are you certain that your agent of choice uses Sodium? It would be very unusual. You haven't mentioned the brand but there are many products on the market that don't use Sodium.
> 
> In any case, I don't think 30ppm or the buildup due to water changes will be too much of a problem based  on some studies done (at least for those particular species), such as https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwjXsf_pptzcAhVKr1QKHbDVBlMQFjAAegQIABAC&url=https://pdfs.semanticscholar.org/0267/c4beb3a9bf85910fe996a42e4ebf08223382.pdf&usg=AOvVaw1gM_fpSvV0HkxJW7scwpyH
> as well as https://www.jstor.org/stable/1351922?seq=1#page_scan_tab_contents
> ...


Thanks for your reply.

The product to which I am referring is_ Re-Mineral Tropic,_ which is made by Tropic Marin. I have an email from them confirming that, when mixed with RO water as instructed, the resulting sodium concentration is 31.9mg/l. They are of the view that this is not a problem but I see no reason for the sodium to be in their product in the first place. Consequently, I will soon switch. I am tempted to go for the mix suggested at http://www.theplantedtank.co.uk/RO.htm. Or one of Seachem's offerings.

Thanks also for the links, which I will read this evening.


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## dw1305 (8 Aug 2018)

Hi all, 





jaypeecee said:


> They are of the view that this is not a problem but I see no reason for the sodium to be in their product in the first place





dw1305 said:


> A lot of commercial re-mineralising salt mixes have NaCl or NaHCO3 in them as a "filler", because it is the cheapest option, and all the talk about "_osmotic pressure_" etc. is just "_smoke and mirrors_".


It is in the salt mix as a cheap filler.





dw1305 said:


> Pretty much, there is actually similar reserves of sodium and potassium on the earth, but because plants don't have a sodium requirement the sea is salt with NaCl (the Cl has accumulated for similar reasons).


I've subsequently found out that this isn't strictly true, and that most of the Na+ Cl- ions in sea water are there from strictly geological processes (hydrothermal vents) and the the biogenic effect is comparatively minor. 

cheers Darrel


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## tam (8 Aug 2018)

I'm sure I've seen it specifically stated that Re-min Tropic doesn't contain NaCl. I know it's popular with discus keepers. My plants seem to grow fine with it, but in fairness they are the more easy/hardy types.


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## alto (9 Aug 2018)

The Na may be showing up as Na Phosphate, Na Nitrate etc ... the sodium version of various salts is always cheaper than the K (potassium) version


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## AverageWhiteBloke (9 Aug 2018)

Like DW says then, using sodium as a cheaper filler than potassium.

Sent from my STH100-2 using Tapatalk


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## jaypeecee (10 Aug 2018)

tam said:


> I'm sure I've seen it specifically stated that Re-min Tropic doesn't contain NaCl.


Yes, that would stack up. I was informed by Tropic Marin that "In Re-Mineral Tropic sodium and chloride are not in the form of common table salt".


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## rebel (12 Aug 2018)

Wouldnt it be easier to chuck some CaCO3 in the filter. Ie some coral rubble ..that will self regulate your Kh .


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## jaypeecee (15 May 2019)

Hi Folks,

I'm re-visiting this thread to add a recent observation. Although I don't use tap water in my tanks, I note that sodium in my tap water last year ranged from 19.0 - 37.6 mg/l. Not only that but the PCV (Prescribed Concentration or Value) is currently 200 mg/l. These figures are taken directly from the South East Water Crowthorne Water Supply Zone annual report 2018.

Food for thought?

JPC


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## jaypeecee (15 May 2019)

Me again!

Rather than editing my post above (#20), I really would like to resurrect this thread even though it was started over four years ago (by GlassWalker). The thread focused on potassium but the OP's question concerned sodium. There appears to be some uncertainty about sodium in planted tanks - both for plants and fish. Seachem has the following to say about their _Equilibrium_ product geared towards RO/DI water remineralization:

"Unlike competing products, Equilibrium™ contains NO SODIUM CHLORIDE. Both sodium and chloride are not rapidly depleted elements in a planted aquarium, and, in the case of chloride, can do more harm than good. Competitors’ products generally contain primarily sodium chloride (because it is inexpensive), which will raise the electrolyte levels for fish, but can be detrimental to plant growth. In addition, sodium is not a contributing cation to GH levels. Equilibrium™ contains only calcium, magnesium, and potassium salts, which aid in fish metabolism, but are also highly beneficial to plant growth".

Would anyone care to comment?

JPC


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## alto (15 May 2019)

It’s one of the reasons I use Equilibrium (erratically I must confess)

There’s no doubt that NaCl is damaging to aquatic plants, though some are much more tolerant than others, eg, Anubias and some Vallisneria sp. will tolerate estuary saline tanks (though I’ve seen few examples when the plants thrive as they might in non-salt scapes)


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## dw1305 (15 May 2019)

Hi all,





jaypeecee said:


> I note that sodium in my tap water last year ranged from 19.0 - 37.6 mg/l


You get a bit of sodium naturally in water from limestone aquifers, evaporite deposits, volcanic deposits etc., but if you have a supply with some surface water in it you can get a pulse of  sodium from salt (NaCl) based road de-icers in the winter.

cheers Darrel


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## jaypeecee (21 May 2019)

Hi Folks,

I got some more information from Seachem as follows:

[1] "Sodium chloride tends to dehydrate the leaves of the plant which can result in yellowing or necrosis. Excess sodium can also interfere with potassium uptake, which is why we recommend avoiding sodium chloride based products when keeping a planted aquarium!

Here's a helpful study that was conducted about general plant biology and the plant response to Na+, CL- and NaCL:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2955754/"

[2] "The tolerance of plants for sodium/ sodium chloride varies widely. On the low end, plants can start to show negative symptoms with around 10 mg/L of sodium chloride present, while other plants can tolerate up to 1000 mg/L. I would say as a general rule, anywhere above about 100 mg/L would be considered "elevated levels"

[3] "The sodium ion becomes a problem at a higher concentration than sodium chloride. If someone is continuously using sodium bicarbonate to buffer the water, and only rarely changing the water, then sodium can build up to detrimental levels, but under normal circumstances, sodium bicarbonate can be used as a buffer in planted tanks without issue".

I find the above information useful. I hope it's also useful to other UKAPS users.

JPC


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## dw1305 (21 May 2019)

Hi all,





jaypeecee said:


> I got some more information from Seachem as follows:


That looks a reasonable reply. 





jaypeecee said:


> 2] "The tolerance of plants for sodium/ sodium chloride varies widely.On the low end, plants can start to show negative symptoms with around 10 mg/L of sodium chloride present, while other plants can tolerate up to 1000 mg/L. I would say as a general rule, anywhere above about 100 mg/L would be considered "elevated levels"


That would be the real heart of it for me, we aren't going to know for a lot of plants what their NaCl  tolerance is, because there won't be any published data for them. 

You can make some educated guesses, based upon the tolerances of terrestrial crop plants. Some crop plants are really intolerant of any salt in their irrigation water, there are figures for the sensitive plants like _Vaccinium_ spp. (Blueberries - _V.  angustifolium/V. corymbosum & _Cranberry _V. macrocarpon_)  and  for ornamentals like _Anthurium, _Orchids, Bromeliads, Gesnerids and _Begonia_ spp.

I'd be pretty confident plants from harder water are more likely to be sodium (Na+), and salt (NaCl), tolerant than those from soft water. Lake Tanganyika is sodium rich (as well as being very hard), so <"any of the plants that grow in it"> must be sodium tolerant. 





jaypeecee said:


> [3] "The sodium ion becomes a problem at a higher concentration than sodium chloride. If someone is continuously using sodium bicarbonate to buffer the water, and only rarely changing the water, then sodium can build up to detrimental levels, but under normal circumstances, sodium bicarbonate can be used as a buffer in planted tanks without issue".


I'm not sure about that one, I'd definitely avoid NaHCO3 as a buffer unless I kept a planted tank with <"Lake Tanganyika"> fish. 

It could be a conductivity effect (Na+ and Cl- are both highly conducting ions), but I wouldn't expect that to be particularly marked compared to other sodium compounds. 

All sodium compounds are soluble, so when you put them into water the sodium will go into solution as Na+ ions, and every Na+ ion is the same as every other Na+ ion, whether it came from NaCl (Na+ & Cl-) or sodium bicarbonate NaHCO3 (Na+ & HCO3-). 

cheers Darrel


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## jaypeecee (24 May 2019)

dw1305 said:


> I'd definitely avoid NaHCO3 as a buffer unless I kept a planted tank with <"Lake Tanganyika"> fish.
> 
> cheers Darrel



Hi Darrel,

Many thanks, as always, for your feedback.

I have picked out your statement above. What would you use instead of NaHCO3? Would KHCO3 be a better choice? Is it readily available?

JPC


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## dw1305 (24 May 2019)

Hi all,





jaypeecee said:


> What would you use instead of NaHCO3? Would KHCO3 be a better choice? Is it readily available?


Yes, I would use potassium bicarbonate (KHCO3). 

It is widely available as "food grade" for auction sites etc. I had a quick look on amazon and a kilogram was about £8. 





dw1305 said:


> adding1.8g KHCO3 to 25 litres of water adds 2 dKH (from <"James' Planted Tank">).



cheers Darrel


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## jaypeecee (24 May 2019)

dw1305 said:


> Hi all,Yes, I would use potassium bicarbonate (KHCO3).
> 
> It is widely available as "food grade" for auction sites etc. I had a quick look on amazon and a kilogram was about £8.
> 
> cheers Darrel



Thanks a lot, Darrell.

I'll look for a much smaller quantity as I don't think I'll get through a kilogram of the stuff - not in this lifetime, anyway!

JPC


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