Lowering Alkalinity with sodium bisulfite

[miller75]

I am about to start lowering my Alkalinity with sodium bisulfite by adding it to my new salt mix, how long after adding the sodium bisulfite should I start aerating it?

 

[edsbeaker]

I am about to start lowering my Alkalinity with sodium bisulfite by adding it to my new salt mix, how long after adding the sodium bisulfite should I start aerating it?

Could you please tell us what your alkalinity is at? Before adding chemicals to reduce it, if it is higher than you want could you just let it come down naturally, or switch to a salt with a lower alkalinity? I’m just trying to help find a solution that doesn’t involve adding products. My thoughts have always been that when you start to add products to change parameters it sometimes leads to more problems.

 

[miller75]

Could you please tell us what your alkalinity is at? Before adding chemicals to reduce it, if it is higher than you want could you just let it come down naturally, or switch to a salt with a lower alkalinity? I’m just trying to help find a solution that doesn’t involve adding products. My thoughts have always been that when you start to add products to change parameters it sometimes leads to more problems.

In the tank its currently at 12dkh and rising, I am not dosing anything so I think its coming from my sand bed. The tank is pretty new and I only have 3 small torches so I dont have enough in there to prevent the rise

 

[Garf]

In the tank its currently at 12dkh and rising, I am not dosing anything so I think its coming from my sand bed. The tank is pretty new and I only have 3 small torches so I dont have enough in there to prevent the rise

Are you adding tap water?

 

[X-37B]

I am about to start lowering my Alkalinity with sodium bisulfite by adding it to my new salt mix, how long after adding the sodium bisulfite should I start aerating it?

Aerate as you lower it. It takes awhile for ph to come up and aeration helps.

 

[miller75]

Are you adding tap water?

I am making my own RODI. I have replaced all the filters and had an icp done which can back fine on the RO water

 

[Garf]

I am making my own RODI. I have replaced all the filters and had an icp done which can back fine on the RO water

What Alk test kit are you using? It's not at all normal for increasing alkalinity without adding it, lol. You are adding RODI to replace evaporation, I assume? Have you measured the Alk of your new saltwater?

 

[edsbeaker]

In the tank it’s currently at 12dkh and rising, I am not dosing anything so I think its coming from my sand bed. The tank is pretty new and I only have 3 small torches so I dont have enough in there to prevent the rise

That’s strange. I’m not sure why it would be continuing to rise if you are not dosing.

What test kit are you using to measure it?

 

[EnterName]

Alkalinity rarely rises on its own, there must be some underlying reason, and I feel like it is pretty important to understand what's happening.

What makes you think it is coming from your substrate? Sure Aragonite (mostly CaCO₃) has some buffering capacity but it doesn't simply go into solution in large quantities.

 

[miller75]

I am using KH director and Hanna backed up with ICP, I am using Red Sea blue and that comes out at 8.2 dkh.

The substrate is my final option after eliminating everthing else and reading quite a few threads on here, I would normally be saying salinity is out or its been doesed but the only this I have hooked up to my doser is nopox and I have only been dosing that for a week or so.

My plan is to reduce my fresh salt mix to 7dkh and try and lower it that way, I am asuming that it will only release so much and the stop.

This is the sand I am using https://reeflowers.com/urunler/kum/category-product-detail/PWS7K1?lang=en

 

[miller75]

Just spotted my typo, I am using sodium bisulfate not bisulfite, its acually Seachen Acid Buffer

 

[EnterName]

This is the sand I am using https://reeflowers.com/urunler/kum/category-product-detail/PWS7K1?lang=en

If the substrate is actually the cause there has to be something wrong with it. CaCO₃ won't simply dissolve into water or all aragonite substrates would have the same issue.

NO₃:PO₄-X is essentially carbon dosing with ethanol, methanol, and acetic acid and is very alkalinity neutral in itself. In theory nitrate assimilation does rise alkalinity, but this effect is cancelled by the conversion from ammonia to nitrate. In other words: A continuously rising alkalinity could only be reached by adding a direct nitrate source that doesn't have to go through the conversion from ammonia to nitrate.
You would need to assimilate a lot of nitrate to get alkalinity up (according to the linked article 50ppm NO₃ for 4.5dKH, which would get your alkalinity from 7.5 to 12dKH).

 

[Randy Holmes-Farley Verified Community Expert]

Just spotted my typo, I am using sodium bisulfate not bisulfite, its acually Seachen Acid Buffer

Yes, a serious typo. I have recipe threads for lowering alk with bisulfate and also muriatic acid. Bisulfite would be a bad addition.

 

[JonasRoman]

I am about to start lowering my Alkalinity with sodium bisulfite by adding it to my new salt mix, how long after adding the sodium bisulfite should I start aerating it?

according to my opinion there is never an indication to chemicaly lowe alkalinity. Because
1) A sudden increase of alk thanks to water change is not bad for corals, its sudden lowering that is bad.
2) Alk is consumed in a natural way, so its just to wait.

When I change water with red sea salt, my alk goes up from approx 7.5 to 8.5. My dosing units shut off the Balling dosing (at the momentn triton 7), and after 1 day its back to 7.5 and dosing kicks in again.

Its only in the spa bath you dose NaHSO4;-)..

Jonas

 

[JonasRoman]

In the tank its currently at 12dkh and rising, I am not dosing anything so I think its coming from my sand bed. The tank is pretty new and I only have 3 small torches so I dont have enough in there to prevent the rise

I do not think its possible that you sand bed incresase alk. If you put pure sand in RO water, we know that it can slowly add carbonates to the water, but not more than mayve 1.5 dKH. Now we have a marine water, so CaCO3 will not dissolve, and hence not reelease any alkalinity.

First I would verify the values, are you testing correct? KH can increase by denitrification activity BUT thats also unlikely in your case as the tank is new. As tank is new it will rather be the opposite , that nitritfiation that soon kicks in, will consume alk.

 

[JonasRoman]

I am using KH director and Hanna backed up with ICP, I am using Red Sea blue and that comes out at 8.2 dkh.

The substrate is my final option after eliminating everthing else and reading quite a few threads on here, I would normally be saying salinity is out or its been doesed but the only this I have hooked up to my doser is nopox and I have only been dosing that for a week or so.

My plan is to reduce my fresh salt mix to 7dkh and try and lower it that way, I am asuming that it will only release so much and the stop.

This is the sand I am using https://reeflowers.com/urunler/kum/category-product-detail/PWS7K1?lang=en

I would doublecheck alka with a manual titration test, its most reliable. ICP is not a good comparing methods, as ICP do not measure alk, so the lab just do same titration test as you do, and as sample is old , the KH value from icp labs is not useful info.
KH director I dont know how stable it is, but all machines can failure like drifting electrodes etc. Hanna KH is also not so easy, as its not using titration, so its not super accurate.
So double check with a salifert Kh test or similar.
ALk is one of those things that never is strange, its just math.

/Jonas

 

[EnterName]

Just spotted my typo, I am using sodium bisulfate not bisulfite, its acually Seachen Acid Buffer

Yes, a serious typo. I have recipe threads for lowering alk with bisulfate and also muriatic acid. Bisulfite would be a bad addition.

Sorry to bother you, but any idea how alkalinity keeps rising for OP? This is the second post within 48h I have seen reporting rising alkalinity without obvious source.

 

[Randy Holmes-Farley Verified Community Expert]

Sorry to bother you, but any idea how alkalinity keeps rising for OP? This is the second post within 48h I have seen reporting rising alkalinity without obvious source.

Alk can rise from several sources:

1. Falling or dosing nitrate. Its consumption adds alk.

2. Slow dissolution of rock and sand down inside it where pH is low. This generally always happens at a low rate and is lost in larger demands, but in a no demand tank, can be significant.

3. Top off with tap water that has alk.

4. Water changes with a mix that has higher alk than the tank.

5. Additions via products that may have alk you are not aware of.

6. Dosing pump issues.

7. Recipe for alk solutions not followed correctly.

8. Finally, maybe it sn’t rising: it’s a testing problem.

 

[EnterName]

@miller75 do you remember your nitrate levels before starting NOPO-X?

To get from 8.2dKH (your initial salt mix) to 12dKH you would need to get rid of like 42ppm nitrate... That's quite a lot. Maybe multiple factors are contributing to the issue.

 

[miller75]

@miller75 do you remember your nitrate levels before starting NOPO-X?

To get from 8.2dKH (your initial salt mix) to 12dKH you would need to get rid of like 42ppm nitrate... That's quite a lot. Maybe multiple factors are contributing to the issue.

This has been going on for a couple of months well before i started dosing nopox.

My nitrates are only about 15, I am using it to get my phosphates down a bit becasue I didnt have any GFO to hand