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Discussion Starter · #1 · (Edited)
I composed this message in response to all the fear mongering about adding any sodium (Na+), mainly in the form baking soda to increase KH. Baking soda contains bicarbonates that can be used as a carbon source by many aquatic plants.

The attack on sodium is reminiscent of the kerfuffle over chloride, another abused element that has been accused--wrongfully-- of toxicity. These elements are not toxic in small amounts.

Moreover, plants take up Na, so when you prune plants you are in essence removing Na. Attached is the sodium composition found in 5 aquatic plants by scientists. When you add a small dose (1 tsp/10 gal) of baking soda to a tank, the sodium it contains can be removed when you prune plants.

I calculated that 1 teaspoon of baking soda/10 gal (7g/38 liters) is 0.018% NaHCO3. Since the % of Na in NaHCO3 is 27%, the Na concentration is 0.005%, which is 50 ppm.

Median Na concentration of natural waters is 6 ppm with a range of 0.7 to 25 ppm (Reference: Bowen 1979). Thus, the baking soda addition I recommended produces a Na level (50 ppm) that is much greater than that found in natural waters. (Whether this inhibits plant growth or not is another question.) Therefore, go easy on adding baking soda to your tanks.
 

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A dumb question, but any idea if the sodium taken up by plants is visible in the leaves/stems?

I have a 10 gallon that i use for quarantine that I added a small amount of NaCl to while treating some minor fin rot. Initially, some plants died back, mainly vals. Eventually they seemed to recover but the main plant (pearlweed) colonized the whole tank without incident. I can take a pic when I get home, but I noticed many of the stems have some sort of almost crystal looking whiteish matter on the leaves. I always wondered if that was salt taken up by those plants as it was a small amount I added and many of the plants do not have that characteristic.
 

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A dumb question, but any idea if the sodium taken up by plants is visible in the leaves/stems?

I have a 10 gallon that i use for quarantine that I added a small amount of NaCl to while treating some minor fin rot. Initially, some plants died back, mainly vals. Eventually they seemed to recover but the main plant (pearlweed) colonized the whole tank without incident. I can take a pic when I get home, but I noticed many of the stems have some sort of almost crystal looking whiteish matter on the leaves. I always wondered if that was salt taken up by those plants as it was a small amount I added and many of the plants do not have that characteristic.
Too much salt can block proper nutrient uptake. The plant might look like some sort of nutrient deficiency.
 

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Too much salt can block proper nutrient uptake. The plant might look like some sort of nutrient deficiency.
Plant Terrestrial plant Tints and shades Grass Flowering plant


Here are the best pics I can get. Actually looks like salt crystals on the leaves of the old growth. Did not notice slowed growth or reduced leaf size though
 

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Discussion Starter · #6 · (Edited)
A dumb question, but any idea if the sodium taken up by plants is visible in the leaves/stems?

I have a 10 gallon that i use for quarantine that I added a small amount of NaCl to while treating some minor fin rot. Initially, some plants died back, mainly vals. Eventually they seemed to recover but the main plant (pearlweed) colonized the whole tank without incident. I can take a pic when I get home, but I noticed many of the stems have some sort of almost crystal looking whiteish matter on the leaves. I always wondered if that was salt taken up by those plants as it was a small amount I added and many of the plants do not have that characteristic.
No, neither the salt (NaCl) nor the sodium ion (Na+) would be visible. They stay in solution.
Do you remember how much salt you added? In general, the amount of salt you would need to treat a bacterial infection (kill bacteria) would be much more than most plants could handle. The salt concentration that generally inhibits most aquatic plants in nature is around 0.1% (1,000 ppm). Bacopa monnieri and Salvinia molesta are salt tolerant and can be grown at higher concentrations (~0.5 to 1.5%). Seawater is 3.5%.
And plants don't die immediately. The whitish material may be bacteria feeding off nutrients released by the dying tissue.
 

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Discussion Starter · #7 ·
Any salt treatment for disease is going to be more than plants can handle:
Most aquatic plants cannot tolerate levels above 0.1%. Most disease treatments use much more than this (2-9 teaspoons per gallon)

Calculations: A tablespoon of NaCl weighs 21 grams, so a teaspoon (1/3 of a tablespoon) contains 7 grams.
If you add a teaspoon (7 g NaCl) to a gal (3.8 liters) of water, that translates into 1.8 grams/liter (7 divided by 3.8 = 1.8). Final concentration is 0.18%, which is above the 0.1% plant threshold.
Most people use more than 1 tsp NaCl per gallon in treating fish diseases, so you can see where plants would have a problem.
 

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That makes sense. I had never used salt before so I added a small amount (1-2 tsp in my 10 gallon). The infection got worse the next day so I ended up using metronidazole in the food. All my plants tolerated this small amount well except the Val which ended up recovering after a few weeks.
 
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