Can sodium carbonate cause ionic imbalance?

[srjosepz]

I am adding sodium carbonate to decrease the calcium dissolved in water, that was very very high (more than 1000 mg/l)
Now, after slow precipitation of calcium, its concentration is 580, still high, but much better.

But this seems to be affecting the fish, which are more hidden than before and less active, so I stopped to add more sodium carbonate.
As the rest of values are right, (temperature 26, PH 8.0, salinity 35mg/l, Magnesium 1280, KH 7, nitrate 0, phosphate 0.03) my concern is if the fact of adding only carbonate and not bicarbonate, can cause an unbalance, that could be affecting the fish, or if the system will balance carbonates and bicarbonates by itself, and I must search for another cause of fish behavior change...

I am afraid the sodium carbonate I am using may contain any kind of undesirable waste, because is a PH raiser for swimming pools, even I can read ""100% Na2Co3".

 

[Randy Holmes-Farley]

How did calcium get that high? Overdose? If you don’t know, stop adding the carbonate until we are sure of the value.

How did you measure it? There may just be a unit of measure issue as 1000 ppm calcium carbonate equivalents, as sone kits fir pools measure, is fine.

Yes, regardless of the impurities, you added a lot of sodium and presumably chloride from calcium chloride.

How big is this tank?

 

[srjosepz]

I don't know the real cause of how the calcium was so high, It's been over two years since my 580L aquarium (+ sump) was set up and filled with natural seawater. I never added nothing at all, except reverse osmosis water for compensate evaporation. Natural seawater was used for water changes too. Not very often, to be sincere... at times I did one 10-15% water change monthly, at times , no water changes in 6 months.

As it is an only fish aquarium, and have only two small fish (6 - 7 cms) and things went very well, I only measured temp,salinity, Ph, nitrates and phosphates, monthly. All values was right all the time.

But a little while ago, as I have some more free time now, I decided to add easy corals and more fish. So, I did an ICP test before add it. This was how I noticed the calcium high level, (and magnesium ver very low...) I posted the result in another post here... My suspect is part of the live sand was dissolved due the low magnesium level (less than 500 then)

So I removed the gravel, got the testers, confirmed the values, and added the magnesium to the right level, and then the sodium carbonate (never added calcium) to precipitate the excess of calcium, slowly.

Right now, calcium is 580mg/l but the fish seems affected. So, I stopped to add sodium carbonate. And I started to wonder if by only adding sodium carbonate and not bicarbonate, I would be creating an imbalance between carbonates and bicarbonates, or if these balance themselves out later.

 

[Randy Holmes-Farley]

IMO, you are worried about the wrong things. Carbonate vs bicarbonate makes no difference.

Low magnesium does not cause calcium carbonate sand to dissolve.

What calcium kit are you using now?

I do not believe the tank can get to 1000 ppm calcium without additions.

Do you have the icp?

Calcium at 580 ppm is ok and needs no changes if accurate.

 

[srjosepz]

Thanks for the answer. So, I was wrong. I read sodium carbonate was better than sodium bicarbonate to raise PH and KH, and precipitate calcium. Anyway, it worked....if there is no difference using carbonate or bicarbonate, I'll forget my worries about that. I am using aquaforest calcium test right now.
This is the ICP https://aquaforestlab.com/results/4sNHvyxX72658

 

[Randy Holmes-Farley]

The no difference answer was in relation to ion imbalance. Both work to lower calcium, but I would not have used either if you are convince calcium was really as high as the icp mentioned.

Have you kept track of how much bicarbonate you added?
What size tank?
What calcium kit?

 

[srjosepz]

The no difference answer was in relation to ion imbalance. Both work to lower calcium, but I would not have used either if you are convince calcium was really as high as the icp mentioned.

Have you kept track of how much bicarbonate you added?
What size tank?
What calcium kit?

So, there's no ion imbalance, right?
About how much carbonate I added — (I didn’t add bicarbonate, just carbonate) — well, yes and no.
I know how much sodium carbonate I added, but since I’ve been doing water changes over the past few weeks, I’m not exactly sure how much has been removed.
The total amount of sodium carbonate I’ve added over these weeks is close to 1000 grams.
The aquarium holds about 650 liters of water in total.
I used the Aquaforest calcium test kit at the beginning, and now I’m using the Salifert calcium test kit.

 

[Randy Holmes-Farley]

Yes, there’s an imbalance caused by sodium, not bicarbonate/carb.

 

[Randy Holmes-Farley]

The amount of alk you added (1,000 grams sodium bicarbonate) is about 51 dKH, and if all was consumed making calcium carbonate, would deplete about 366 ppm of calcium in 650 L, so the decline you see is plausible.

I’d ignore the ion imbalance until you get another icp some time in the future to check things like potassium. In the meantime, I’d raise the salinity to 35 ppt (sg = 1.0264) to help boost things like potassium that may be a bit low due to the sodium additions).

 

[srjosepz]

Yes, there’s an imbalance caused by sodium, not bicarbonate/carb.

The amount of alk you added (1,000 grams sodium bicarbonate) is about 51 dKH, and if all was consumed making calcium carbonate, would deplete about 366 ppm of calcium in 650 L, so the decline you see is plausible.

I’d ignore the ion imbalance until you get another icp some time in the future to check things like potassium. In the meantime, I’d raise the salinity to 35 ppt (sg = 1.0264) to help boost things like potassium that may be a bit low due to the sodium additions).

Thanks for your support. Since the ICP test, I’ve been increasing salinity through water changes, and I assume those changes have also helped control the calcium levels. KH is still a bit low, although it has gone up from 5.6 to 7. Magnesium keeps getting consumed — I’m not exactly sure why — but I’ve been adding it and keeping it around 1300. I don’t think I’ll add anything to raise the KH for now; I don’t want to stress the fish any further. I’ll just continue with water changes, and at some point I’ll order another ICP test

 

[Randy Holmes-Farley]

Precipitation of calcium carbonate will also take down magnesium a bit as it gets incorporated.

 

[srjosepz]

Precipitation of calcium carbonate will also take down magnesium a bit as it gets incorporated.

That explains it. THANKS.
The puzzle is starting to come together in my head. I suppose that even without having animals that directly consume calcium or magnesium from the water, the nitrification process, along with oxidation processes, uses up carbonates, calcium, and magnesium. This lowers the KH, allowing calcium from the sand to dissolve, which increases the dissolved calcium to the levels I observed, while the rest decreases.
So, this means that these parameters need to be monitored regardless of the animals you keep — they’ll be consumed to a greater or lesser extent, but they will be consumed. Lesson learned. :)