Alkalinity rising without dosing... possible causes?

[sagedrake690]

Aren't mineral acids highly deadly though? I alway been afraid to put HCL in there for fear of how strong it would be. What is the dosage for a 55gal and how do you increase PH without skyrocketing alkalinity?

 

[Randy Holmes-Farley]

Aren't mineral acids highly deadly though? I alway been afraid to put HCL in there for fear of how strong it would be. What is the dosage for a 55gal and how do you increase PH without skyrocketing alkalinity?

Lots of pepel use muriatic acid (HCl) to drop alk in new salt water.

The strength of the acid makes no difference to the pH change when it is fully ionized regardless.

For example, adding acetic acid (vinegar, pKa ~5) and HCl (pKa below 0) will both drop pH exactly the same amount per units of alk consumed (and the vinegar gives it all back when it is metabolized).

 

[GlassMunky]

Seems an odd solution that I would not recommend as there are far simpler and cleaner methods. Tannic acid will bind trace metals and impact bioavailability, will potentially yellow the water, and may ultimately be metabolized, releasing some or all of the alkalinity back.

If one really wants to lower alkalinity in a running reef tank without doign water changes with a low alk mix, one way is to do them with a super low alk mix that you make yourself, or by very, very slowly adding a mineral acid to the tank. Sodium bisulfate (like Seachem acid buffer) or hydrochloric acid will permenently lower the alk and do little else besides lower pH when first added (which tannic acid will also lower pH to the same degree per unit of alk depleted).

I’ve used HCL in my mixing container before on rare occasions, but didn’t think it was ok to dose it to the DT full of fish because it would drop pH as well.

What dosage would you recommend starting at for a 220G tank with 65G sump? Maybe start low with a total of 2ml and see how that effects pH?
The tank runs 8.0-8.3 ph every day.

 

[Randy Holmes-Farley]

I’ve used HCL in my mixing container before on rare occasions, but didn’t think it was ok to dose it to the DT full of fish because it would drop pH as well.

What dosage would you recommend starting at for a 220G tank with 65G sump? Maybe start low with a total of 2ml and see how that effects pH?
The tank runs 8.0-8.3 ph every day.

Any acid used to drop alkalinity will drop pH by the same amount for a fixed alk drop.

The method does drop pH, and it is not best done in a reef tank. My preferred method is to drop water change water to very low alk (say, 1 dKH), aerate to drive off the excess CO2, then do a water change. But if added very slowly, can work out. Like putting a tiny bit in an ATO.

I wouldn't recommend any amount without know what the alkalinity is and what the goal is.

But adding enough acid to drop the alkalinity by 1.4 dKH dropped pH in new Instant Ocean salt mix from pH 8.1 to 6.91 in my testing. Thus, I think that if alk is high, that if one added enough acid to drop the tank alk by 0.02 dKH at a time, there is little to no concern about pH (as long as it is not added near an organism, but can mix in well before encountering organisms).

I showed that here:

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

Randy answers many questions in this complex relationship.

reefs.com

 

[Simbol]

Hello All from the UK,

I am experiencing this issue and I suspect my Sand since I am using Marco Rock.. In my case I am using Aquamedic Bali Sand which is apparently made of 98% calcium carbonate.

I am at lost with this because my tank is 700Liters and the amount of water changes I have been doing is not only exhausting.. but very expensive! I am now using HCI to control it.. but this is not a long term solution.. I am new to the hobby the tank has been running for less than 8 months and I feel like I want to give up.. so any help would be appreciated.

This is the only forum where I have found so many people with the same issue as I have.. so at least I know now I am not losing my mind.

If I were to replace my sand, what is the best sand to use in order to avoid this problem? Aragonite is clearly an issue.. mine is also problematic, so what is the alternative?

What is the best way to change the sand? 1/3 per week?

Thanks in advance,
Raul from UK

 

[sgrosenb]

Hi @Simbol sorry for your tank woes. But my advice would be - don't give up! Using acid to lower the alk via something like Seachem Acid Buffer will work, but for me, removing the sand did the trick. I personally really like the look of sand, but I found that it's easier to just remove. I have since bought some LPS to fill some of the bottom of the tank, and I think my goal will be to just fill the bottom with all LPS. It also makes water changes wayyyy easier - no need to sift sand you just take the water out and replace. Overall, I'm a lot happier with no sand.

In terms of taking it out, I do believe it's a destabilizing event. Given that your tank is 8 months old, I'd take it slow. Maybe 1/4 per week and finish in a month, with a water change after each sand removal. Others might have another opinion, but I did it at about that speed and it was fine.

Good luck!!! Let us know how it goes

 

[Randy Holmes-Farley]

Hello All from the UK,

I am experiencing this issue and I suspect my Sand since I am using Marco Rock.. In my case I am using Aquamedic Bali Sand which is apparently made of 98% calcium carbonate.

I am at lost with this because my tank is 700Liters and the amount of water changes I have been doing is not only exhausting.. but very expensive! I am now using HCI to control it.. but this is not a long term solution.. I am new to the hobby the tank has been running for less than 8 months and I feel like I want to give up.. so any help would be appreciated.

This is the only forum where I have found so many people with the same issue as I have.. so at least I know now I am not losing my mind.

If I were to replace my sand, what is the best sand to use in order to avoid this problem? Aragonite is clearly an issue.. mine is also problematic, so what is the alternative?

What is the best way to change the sand? 1/3 per week?

Thanks in advance,
Raul from UK

An easier solution than replacing the sand may be to add more organisms that consume calcium carbonate.

But if you want to replace the sand, then a natural silica sand (like beach sand) would be a good plan.

Also, make sure you are not using tap water for top off as it can add a lot of alkalinity.