Sandbed turning hard as rock- pH the cause ?

[Holst]

Hi R2R.

I have noticed that my sandbed is turning hard as rock. I do have sand shifting starfish, snails, goby's etc.
I have the suspicion that my elevated pH 8,35-8,55 is making the calcification going on in the sandbed as well and not only helping the corals to grow fast and strong.
I am running with a little elevated parameters.
CAL: 460
ALK 9
MG 1400
pH 8,35 during night. 8,55 during day.

I am thinking about shutting down the Co² scrubber because it is hard to maintain constant levels.
And is this also a side effect of running with the co² scrubber and high pH ?

Thank you all

 

[Anthony Scholfield]

Hi R2R.

I have noticed that my sandbed is turning hard as rock. I do have sand shifting starfish, snails, goby's etc.
I have the suspicion that my elevated pH 8,35-8,55 is making the calcification going on in the sandbed as well and not only helping the corals to grow fast and strong.
I am running with a little elevated parameters.
CAL: 460
ALK 9
MG 1400
pH 8,35 during night. 8,55 during day.

I am thinking about shutting down the Co² scrubber because it is hard to maintain constant levels.
And is this also a side effect of running with the co² scrubber and high pH ?

Thank you all

When i had some issues with my sand bed becoming clumped and hard i found the issue was from precipitation. This happened in the early stages of the tanks maturity and is no longer a problem. I just broke it up as i found the clumps.

I dont think a elevated PH will cause this, i could be wrong though. My tanks run at a pretty constant 8.3-8.5 without any clumping and my parameters are near yours.

 

[Holst]

When i had some issues with my sand bed becoming clumped and hard i found the issue was from precipitation. This happened in the early stages of the tanks maturity and is no longer a problem. I just broke it up as i found the clumps.

I dont think a elevated PH will cause this, i could be wrong though. My tanks run at a pretty constant 8.3-8.5 without any clumping and my parameters are near yours.

Thank you for your reply @Anthony Scholfield .
I will brake it up and see how it goes in the future. I might be a little more aggressive with the Turkey baster in the sandbed.

Have a nice weekend mate

 

[Waters]

I agree.....seems to happen much more often in new tanks....PH levels really didn't affect mine at all. If you keep breaking it up you should be fine. I ended up removing my sand bed and pulled large dollar bill sized chunks of "concrete" out. After removing my sandbed, my ALK and CA consumption dropped by almost 75%. Everything I was dosing was being absorbed by the substrate.

 

[Gtinnel]

I agree that it's normally calcium carbonate precipitation that causes a hard sand bed. Your levels of alk/cal look normal though. Do you dose anything (2 part, kalk, etc) and if so do you have to dose huge amount(s) to maintain your parameters?

 

[Doreno]

Hi R2R.

I have noticed that my sandbed is turning hard as rock. I do have sand shifting starfish, snails, goby's etc.
I have the suspicion that my elevated pH 8,35-8,55 is making the calcification going on in the sandbed as well and not only helping the corals to grow fast and strong.
I am running with a little elevated parameters.
CAL: 460
ALK 9
MG 1400
pH 8,35 during night. 8,55 during day.

I am thinking about shutting down the Co² scrubber because it is hard to maintain constant levels.
And is this also a side effect of running with the co² scrubber and high pH ?

Thank you all

this is due to a bacterial outbreak, when there is too much bacterial mucus, it just sticks together small grains of sand

 

[Anthony Scholfield]

this is due to a bacterial outbreak, when there is too much bacterial mucus, it just sticks together small grains of sand

I do not believe this is correct. Curious where you got this kind of information?

Could you explain more? What kind of bacteria and from where? What does the mucus look like? Is it sticky?

 

[Doreno]

I do not believe this is correct. Curious where you got this kind of information?

Could you explain more? What kind of bacteria and from where? What does the mucus look like? Is it sticky?

This is from my own experience.

The first time I had grains of sand stuck together and a local stone formed when a bacterial outbreak occurred. But education was local, but large enough.
At that moment I had 1-2mm sand, quite large grains of sand. But even they were very firmly glued together.
Back then, bacterial mucus was everywhere, on the wires, even a little on the filter sock.
It is also very important to note that this effect (clumping) was probably achieved together with diatoms, as the mucus quickly turned brown. It did not last long, but when the diatoms and bacterial outbreak left, the stuck together sand could not be reversed into original, I even hit it hard with a large magnet, it only helped.

The second time there was a dino outbreak (yes, these are not bacteria), and the sand was finer -0.25-1mm, and the sand seemed to be covered with a crust over the entire surface, and stick together, but only on the surface, as if it had dried out.

 

[outhouse]

Been dealing with this for decades, all my sand clumps without manually breaking it up. It is bacterial in nature and not due to precipitation. But to be clear the bacteria is causing precipitation. I get areas that turn to rock, where I cannot turn the sand bed over. Once the tank matures past 5 years, I dont get the bacteria and the sand bed remains as it is supposed to. I have ran threads at RC for decades with no answers about new tanks when I rebuild my sand bed, I get white dots growing on glass that is not precip, which shows how factual the bacteria hypothesis is. Im hoping stuff like Vibrant helps this when I rebuild my DSB in the future.

 

[T-J]

When i had some issues with my sand bed becoming clumped and hard i found the issue was from precipitation. This happened in the early stages of the tanks maturity and is no longer a problem. I just broke it up as i found the clumps.

I dont think a elevated PH will cause this, i could be wrong though. My tanks run at a pretty constant 8.3-8.5 without any clumping and my parameters are near yours.

100% THIS. It's the alk and calc, not the pH. Once the tank matures and you have a good consumption of these, it won't be an issue. In the meantime, you can just breakup the sand chunks.

 

[outhouse]

I do not believe this is correct.

If it wasnt correct, the precip would continue and not stop, not only that, it only took a week, and i get a layer 1/8 " deep that forms a crust right off the bat, precip by itself takes much longer then a week. And with normal parameters, you cannot blame precip

 

[outhouse]

Once the tank matures and you have a good consumption of these, it won't be an issue.

Nope. when I rebuild my DSB my display tank is fully stocked, and completely broke in with no cycle. I grow branching hammer professionally and rbta.

 

[Randy Holmes-Farley Verified Community Expert]

New sand that is missing a coating of phosphate/magnesium/organics/bacteria that all prevent precipitation of calcium carbonate, along with high pH and high alkalinity are the usual drivers of hardening sand.

Here's my usual recommendation:


1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

 

[Randy Holmes-Farley Verified Community Expert]

100% THIS. It's the alk and calc, not the pH.

In any given tank it may not be pH that is driving it, but in general, a rise of 0.3 pH units is the same as a doubling of the alkalinity (say, 7 to 14 dKH) or calcium (say, 400 to 800 ppm) in terms of the potential for precipitation of calcium carbonate. So it can be a big driver.

 

[T-J]

In any given tank it may not be pH that is driving it, but in general, a rise of 0.3 pH units is the same as a doubling of the alkalinity (say, 7 to 14 dKH) or calcium (say, 400 to 800 ppm) in terms of the potential for precipitation of calcium carbonate. So it can be a big driver.

Wow, that's interesting. So if we're having daily pH swings of that amount (I do, even with a CO2 scrubber during the summer), does that mean it's negatively affecting my corals as well? What are the effects of this precipitation on corals?

 

[Randy Holmes-Farley Verified Community Expert]

Wow, that's interesting. So if we're having daily pH swings of that amount (I do, even with a CO2 scrubber during the summer), does that mean it's negatively affecting my corals as well? What are the effects of this precipitation on corals?

I do not know that corals are concerned with the pH swing or not, but I posed the question in a previous thread whether alk stability (which many tout) without pH stability was actually any type of stability. What chemical is actually stable if alk is stable and pH is not? Nothing related to alkalinity.

Alkalinity stability? pH stability? Are they even different?

It is currently the dogma of the reef aquarium hobby to say that alkalinity stability is very important for SPS corals, and that pH is not. Often, the very idea of someone trying to optimize pH is called “chasing numbers” as if that statement by itself shows it to be foolish. Since I have...

www.reef2reef.com

 

[ReefGeezer]

I do not know that corals are concerned with the pH swing or not, but I posed the question in a previous thread whether alk stability (which many tout) without pH stability was actually any type of stability. What chemical is actually stable if alk is stable and pH is not? Nothing related to alkalinity.

Alkalinity stability? pH stability? Are they even different?

It is currently the dogma of the reef aquarium hobby to say that alkalinity stability is very important for SPS corals, and that pH is not. Often, the very idea of someone trying to optimize pH is called “chasing numbers” as if that statement by itself shows it to be foolish. Since I have...

www.reef2reef.com

Hi Randy. Do changes in CO2 levels change alkalinity (total or otherwise) or just pH?

 

[Randy Holmes-Farley Verified Community Expert]

Hi Randy. Do changes in CO2 levels change alkalinity (total or otherwise) or just pH?

Just pH:

Chemistry and the Aquarium: What is Alkalinity?

Randy provides an overview of alkalinity as to why it's important, how it's measured, and how can it be tested.

reefs.com

Alkalinity Facts
There are several facts about total alkalinity that follow directly from the definition. Unfortunately, some of these have been misunderstood by some hobby authors.

One of these facts is termed The Principle of Conservation of Alkalinity by Pankow (“Aquatic Chemistry Concepts”, 1991). He shows mathematically that the total alkalinity of a sample CANNOT be changed by adding or subtracting CO2. Unfortunately, there is an article available on line, which claims otherwise, and encourages people to “lower alkalinity” by adding CO2 in the form of seltzer water. This is simply incorrect.

Forgetting the math for the moment, it is easy to see how this must be the case. If carbonic acid is added to any aqueous sample with a measurable alkalinity, what can happen?

Well, the carbonic acid can release protons by reversing equations 1 and 2:

(5) H2CO3 ==> H+ + HCO3–

(6) HCO3– ==> H+ + CO3—

These protons can go on to reduce alkalinity by combining with something that is in the sample that provides alkalinity (carbonate, bicarbonate, borate, phosphate, etc). However, for every proton that leaves the carbonic acid and reduces alkalinity, a new bicarbonate or carbonate ion is formed that adds to alkalinity, and the net change in total alkalinity is exactly zero. The pH will change, and the speciation of the things contributing to alkalinity will change, but not the total alkalinity.

This is not true for strong acids, however. If you add hydrochloric, sulfuric or phosphoric acids (or any acid with a pKa lower than the carbonic acid endpoint), there will be a reduction in the alkalinity.

 

[ReefGeezer]

Just pH:

Chemistry and the Aquarium: What is Alkalinity?

Randy provides an overview of alkalinity as to why it's important, how it's measured, and how can it be tested.

reefs.com

Alkalinity Facts
There are several facts about total alkalinity that follow directly from the definition. Unfortunately, some of these have been misunderstood by some hobby authors.

One of these facts is termed The Principle of Conservation of Alkalinity by Pankow (“Aquatic Chemistry Concepts”, 1991). He shows mathematically that the total alkalinity of a sample CANNOT be changed by adding or subtracting CO2. Unfortunately, there is an article available on line, which claims otherwise, and encourages people to “lower alkalinity” by adding CO2 in the form of seltzer water. This is simply incorrect.

Forgetting the math for the moment, it is easy to see how this must be the case. If carbonic acid is added to any aqueous sample with a measurable alkalinity, what can happen?

Well, the carbonic acid can release protons by reversing equations 1 and 2:

(5) H2CO3 ==> H+ + HCO3–

(6) HCO3– ==> H+ + CO3—

These protons can go on to reduce alkalinity by combining with something that is in the sample that provides alkalinity (carbonate, bicarbonate, borate, phosphate, etc). However, for every proton that leaves the carbonic acid and reduces alkalinity, a new bicarbonate or carbonate ion is formed that adds to alkalinity, and the net change in total alkalinity is exactly zero. The pH will change, and the speciation of the things contributing to alkalinity will change, but not the total alkalinity.

This is not true for strong acids, however. If you add hydrochloric, sulfuric or phosphoric acids (or any acid with a pKa lower than the carbonic acid endpoint), there will be a reduction in the alkalinity.

Thanks Randy. Am I confused or does your explanation mean that the carbonate/bicarbonate ratio might change but not total alkalinity. And is the difference the H+ ions. (I hope ions is the right term... forgive my ignorance if not.)

 

[Randy Holmes-Farley Verified Community Expert]

Thanks Randy. Am I confused or does your explanation mean that the carbonate/bicarbonate ratio might change but not total alkalinity. And is the difference the H+ ions. (I hope ions is the right term... forgive my ignorance if not.)

Yes, that is correct.

As pH rises from removing CO2, bicarbonate drops and carbonate rises and total alk is unchanged.
As pH falls from adding CO2, bicarbonate rises and carbonate drops and total alk is unchanged.