Miracle mud and kh

Cryptocaryon

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Hi, I've have been running miracle mud in my sump for about 4 months and I have noticed it seems to have increased my alkalinity by about 1 dkh and seems to hold it there?!? I no longer need to dose anything. With that said I have a small mixed reef 136litre including sump but everything is growing well. As far as I am aware miracle mud shouldn't raise or maintain alk but I cant attest these findings to anything else
 

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Hello,

I also have miracle mud in my refugium, but I dont think is actually releasing alk to the tank. My question to you is, do you perform water changes regularly? If so, the alk replacement in your tank is coming from water changes, specially if the new water is higher in alk than the alk reading in your tank.
 
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Hello,

I also have miracle mud in my refugium, but I dont think is actually releasing alk to the tank. My question to you is, do you perform water changes regularly? If so, the alk replacement in your tank is coming from water changes, specially if the new water is higher in alk than the alk reading in your tank.
I guess something like that must be happening then if others hadn't noticed this using miracle mud. I did think that myself so tested the kh of a new mix of water but it is 1dkh lower than my DT water just as it had been for over a year prior to adding the mud. The other thing I guess it could have been because I didn't mix the dry salt so could have been a larger dose of kh in the mix? I tried different test kits to confirm my findings. And my kh does not drop over a 1 week period at all despite clear growth
 
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Cryptocaryon

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I guess something like that must be happening then if others hadn't noticed this using miracle mud. I did think that myself so tested the kh of a new mix of water but it is 1dkh lower than my DT water just as it had been for over a year prior to adding the mud. The other thing I guess it could have been because I didn't mix the dry salt so could have been a larger dose of kh in the mix? I tried different test kits to confirm my findings. And my kh does not drop over a 1 week period at all despite clear growth
And yes I do weely water changes
 

Randy Holmes-Farley

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Hi, I've have been running miracle mud in my sump for about 4 months and I have noticed it seems to have increased my alkalinity by about 1 dkh and seems to hold it there?!? I no longer need to dose anything. With that said I have a small mixed reef 136litre including sump but everything is growing well. As far as I am aware miracle mud shouldn't raise or maintain alk but I cant attest these findings to anything else

How much was alk declining per day before the mud?

The mud doesn't generally do much for alk one way or the other, but if nitrate is declining, that boosts alk.
 
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Cryptocaryon

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How much was alk declining per day before the mud?

The mud doesn't generally do much for alk one way or the other, but if nitrate is declining, that boosts alk.
Wow really I didnt realise that about nitrate, how does that process even occur? Alk was only declining about 0.8 dkh per week.
 

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Here's a copy and paste of the section describing it in one of my articles. Equations 2 and 3 show what I am referring to, and I bolded the math section to gauge the magnitude of the effect: nitrate rise of 50 ppm depletes 2.3 dKH of alkalinity. Nitrate drop of 50 ppm raises alk by 2.3 dKH. Steady nitrate is neutral to alk, no matter what else is happening to it.

Alkalinity and the Nitrogen Cycle

One of the best known chemical cycles in aquaria is the nitrogen cycle. In it, ammonia excreted by fish and other organisms is converted into nitrate. This conversion produces acid, H+ (or uses alkalinity depending on how one chooses to look at it), as shown in equation 1:

(1) NH3 + 2O2 --> NO3- + H+ + H2O

For each ammonia molecule converted into nitrate, one hydrogen ion (H+) is produced. If nitrate is allowed to accumulate to 50 ppm, the addition of this acid will deplete 0.8 meq/L (2.3 dKH) of alkalinity.

However, the news is not all bad. When this nitrate proceeds further along the nitrogen cycle, depleted alkalinity is returned in exactly the amount lost. For example, if the nitrate is allowed to be converted into N2 in a sand bed, one of the products is bicarbonate, as shown in equation 2 (below) for the breakdown of glucose and nitrate under typical anoxic conditions as might happen in a deep sand bed:

(2) 4NO3- + 5/6 C6H12O6 (glucose) + 4H2O --> 2 N2 + 7H2O + 4HCO3- + CO2

In equation 2 we see that exactly one bicarbonate ion is produced for each nitrate ion consumed. Consequently, the alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed.

Likewise, equation 3 (below) shows the uptake of nitrate and CO2 into macroalgae to form typical organic molecules:

(3) 122 CO2 + 122 H2O + 16 NO3- --> C106H260O106N16 + 138 O2 + 16 HCO3-

Again, one bicarbonate ion is produced for each nitrate ion consumed.

It turns out that as long as the nitrate concentration is stable, regardless of its actual value, there is no ongoing net depletion of alkalinity. Of course, alkalinity was depleted to reach that value, but once it stabilizes, there is no continuing alkalinity depletion because the export processes described above are exactly balancing the depletion from nitrification (the conversion of ammonia to nitrate).

There are, however, circumstances where the alkalinity is lost in the conversion of ammonia to nitrate, and is never returned. The most likely scenario to be important in reef aquaria is when nitrate is removed through water changes. In that case, each water change takes out some nitrate, and if the system produces nitrate to get back to some stable level, the alkalinity again becomes depleted.

If, for example, nitrate averages 50 ppm at each water change, then over the course of a year with 10 water changes of 20% each, the alkalinity will be depleted by 1.6 meq/L (4.5 dKH) over the course of that entire time period. This process is one of the primary reasons that fish-only aquaria that often export nitrate in water changes need occasional buffer additions to replace that depleted alkalinity.

While the magnitude of the depletion described in the paragraph above is fairly easy to understand, it also can be converted into units that clarify the imbalance. The impact of alkalinity depletion on the calcium and alkalinity demand balance depends, of course, on the amount of calcium and alkalinity added (and consumed) over the course of that same year.
 
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