dKH Mystery

[rhduggan]

We have a bit of mystery with alkalinity. The Red Sea Reef Mature instructions say to calculate the amount of KH Coraline Grow to raise the alkalinity to 8.4 dKH, but no amount seems to budge the number much above 7. BTW our initial alkalinity was 10.0 dKH before starting the Reef Mature process. Today we discovered that it's precipitating as soon as it's dosed (as recommended) into the sump's pump chamber. My daughter stirred up the precipitate so that it would be conveyed into the DT but, as you will see from our testing on the next day, it's not moving the alk much at all.

Reefer Max 200 G2+
Total water volume calculated to be 175 L accounting for rock and substrate displacement.

2024-01-06
Temp: 79 F
Salinity: 1.025 SG
pH: 7.9
KH/Alkalinity: 7.3 dKH
Ammonia 0.17 ppm
Added:
KH Coraline Grow: 19.25 ml
NoPox: 5.25 ml

2024-01-07
Temp: 79 F
Salinity: 1.025 SG
pH: 8.0
KH/Alkalinity: 7.6 dKH
Ammonia 0.14 ppm
Nitrite: 0.095
Added:
KH Coraline Grow: 4.0 ml
NoPox: 5.25 ml

This time we dosed the KH Coraline Grow directly into the DT and watched it precipitate immediately and float around the tank in little bits before settling or being skimmed. Is this at all normal? We don't know. You can see that the massive (but correctly calculated) dose on 1/6 barely budged the dKH, although the pH did come back up to 8.0. Hoping someone here has answers. If not, I'll move on to Red Sea Support.

 

[Randy Holmes-Farley]

You may have been dosing it too fast.

I'd suggest dosing it slowly to a high flow area to reduce precipitation of calcium carbonate, and if that still fails, switch to using baking soda.

It is normal too see transient precipitation of magnesium hydroxide, which will redisoslve, but if one gets solids that cannot redissolve, it is being added too fast.

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com


Figure 3. The transient cloud of magnesium hydroxide that forms when high pH additives are added. In this case, the alkalinity portion of B-ionic was added to a fairly still portion of one of my reef aquaria.

Precipitates When Carbonate Solutions are Added
Many aquarists are familiar with the cloudiness that forms when high pH two-part calcium and alkalinity additive systems are added to marine aquaria. Figure 3 shows the initial cloud that forms, for example, when the alkalinity part of B-ionic is added to a relatively low flow reef aquarium. The initial cloud sinks and spreads out, eventually dissolving. A similar phenomenon is not observed when adding calcium or magnesium salts, but is observed when adding sodium carbonate solutions.

This cloudiness is, at least in part, magnesium hydroxide and is formed when hydroxide ions are added and the local pH rises. Unlike the addition of limewater, which is unlikely to form magnesium carbonate, this may, although I think it unlikely. The reason it might form here is that the addition of the carbonate ions may push the magnesium carbonate solubility product above saturation. The precipitation of magnesium carbonate can be kinetically slow, just as the precipitation of calcium carbonate can be slow, and since this cloudiness forms instantly, magnesium hydroxide is a much more likely candidate. However, if the additive is not rapidly mixed in, or worse yet, if solid globs of the initial precipitate settle out and are very slow to dissolve, then conditions may be ripe for magnesium carbonate (and calcium carbonate) to form.

In any case, any magnesium carbonate that does form will probably dissolve later as the pH returns to normal reef aquarium levels, so whether the initial cloudiness contains any magnesium carbonate or not is not a critical issue. It does not contain calcium carbonate if mixed in reasonably quickly (a couple of minutes or less), as CaCO3 would not dissolve when mixed with seawater (and this material is observed to dissolve).

 

[gbroadbridge]

We have a bit of mystery with alkalinity. The Red Sea Reef Mature instructions say to calculate the amount of KH Coraline Grow to raise the alkalinity to 8.4 dKH, but no amount seems to budge the number much above 7. BTW our initial alkalinity was 10.0 dKH before starting the Reef Mature process. Today we discovered that it's precipitating as soon as it's dosed (as recommended) into the sump's pump chamber. My daughter stirred up the precipitate so that it would be conveyed into the DT but, as you will see from our testing on the next day, it's not moving the alk much at all.

Reefer Max 200 G2+
Total water volume calculated to be 175 L accounting for rock and substrate displacement.

2024-01-06
Temp: 79 F
Salinity: 1.025 SG
pH: 7.9
KH/Alkalinity: 7.3 dKH
Ammonia 0.17 ppm
Added:
KH Coraline Grow: 19.25 ml
NoPox: 5.25 ml

2024-01-07
Temp: 79 F
Salinity: 1.025 SG
pH: 8.0
KH/Alkalinity: 7.6 dKH
Ammonia 0.14 ppm
Nitrite: 0.095
Added:
KH Coraline Grow: 4.0 ml
NoPox: 5.25 ml

This time we dosed the KH Coraline Grow directly into the DT and watched it precipitate immediately and float around the tank in little bits before settling or being skimmed. Is this at all normal? We don't know. You can see that the massive (but correctly calculated) dose on 1/6 barely budged the dKH, although the pH did come back up to 8.0. Hoping someone here has answers. If not, I'll move on to Red Sea Support.

The Red Sea mature kit is designed for use with live rock - did you start with live rock?

In any event stop dosing the Nopox, it can be counterproductive in a new tank.

The precipitation you are seeing will not redissolve, it sounds like you may be adding too fast to an area of your tank with insufficient water flow.

 

[rhduggan]

The Red Sea mature kit is designed for use with live rock - did you start with live rock?

In any event stop dosing the Nopox, it can be counterproductive in a new tank.

The precipitation you are seeing will not redissolve, it sounds like you may be adding too fast to an area of your tank with insufficient water flow.

Yes, we have some live rock from our LFS in the tank. We are people who read, and follow, instructions carefully.

The RS Reef Mature instructions call for (and include) NoPox. See above re: instructions. I respectfully ask that you please provide rationale for following instructions in the first case and not the second.

Again, following instructions, we added the doses to the return pump chamber, which I think would qualify as "high flow" as the chamber is very small. But it doesn't matter as the precipitate forms immediately even when single drops are added right into the return flow in the DT.

 

[gbroadbridge]

The RS Reef Mature instructions call for (and include) NoPox. See above re: instructions. I respectfully ask that you please provide rationale for following instructions in the first case and not the second.

A new tank simply does not have the biological maturity nor the excess nitrates to require the use of organic carbon dosing.

I know the instructions state to use it, however if you wish to avoid problems such as dinoflagellates overcoming the biological limitations inherent in a new tank, my advice would be to put the bottle aside until your tank is mature to the point of requiring nitrate reduction by that advanced method.

You can search these forums for the many folks who have come to grief by carbon dosing too soon.

 

[rhduggan]

I appreciate your elaboration. This gibes with what I got out of Dr. Tim's YouTube video, which is truly the best explanation of the ammonia oxidation cycle I have seen. Unfortunately, I am an IT guy, not a chemist (although my wife is a biochemist, and my daughter is a college junior studying marine biology). My wife was not willing to invest the time to thoroughly digest the video like I am. Dr. Tim mentions how dosing organic carbon is a bad idea, but I could not determine that NoPox, indeed, falls into that category. It did set off alarm bells, but his examples of organic carbon were vodka and "sugars". When in doubt I follow instructions and would think Red Sea could be trusted.

There are so many contradictions in this hobby it's astounding. I've been involved in quite a few different hobbies over the years, and this takes the cake on that score.

 

[gbroadbridge]

I appreciate your elaboration. This gibes with what I got out of Dr. Tim's YouTube video, which is truly the best explanation of the ammonia oxidation cycle I have seen. Unfortunately, I am an IT guy, not a chemist (although my wife is a biochemist, and my daughter is a college junior studying marine biology). My wife was not willing to invest the time to thoroughly digest the video like I am. Dr. Tim mentions how dosing organic carbon is a bad idea, but I could not determine that NoPox, indeed, falls into that category. It did set off alarm bells, but his examples of organic carbon were vodka and "sugars". When in doubt I follow instructions and would think Red Sea could be trusted.

There are so many contradictions in this hobby it's astounding. I've been involved in quite a few different hobbies over the years, and this takes the cake on that score.

NoPox pretty much is Acetic Acid (Vinegar), Ethanol (Vodka), and DI water with a dash of methanol and acetone for tax purposes

Unfortunately there is a lot of misleading information out there, some of it from vendors who should know better.

You can receive a lot of good advice in these forums if you run it though a common sense filter

 

[Randy Holmes-Farley]

". When in doubt I follow instructions and would think Red Sea could be trusted.

There are so many contradictions in this hobby it's astounding. I've been involved in quite a few different hobbies over the years, and this takes the cake on that score.

Without addressing this particular issue, it is worth noting that the goal of companies is to sell products. If that allows you to have a nice tank at the same time, well, that’s just a bonus.

It won’t take you long to realize there are many bogus products sold to reefers.

My suggestion is to initially look to other reefers for advice, not necessarily companies. It will take much longer to determine which companies you should trust, and which you should not without independent verification.

 

[Randy Holmes-Farley]

To be clear, I’m not suggesting the organic carbon dosing is undesirable or that Tim is correct. IMO it has considerable uses.

 

[rhduggan]

To be clear, I’m not suggesting the organic carbon dosing is undesirable or that Tim is correct. IMO it has considerable uses.

To be clear: Dr. Tim just says not to dose organic carbon during tank cycle startup. He doesn't not to do it ever. The rationale is to prevent accelerating the growth of heterotrophic bacteria, which grow much faster, from outcompeting the growth of the chemolithotrophic bacteria you are trying to get started.

 

[Randy Holmes-Farley]

To be clear: Dr. Tim just says not to dose organic carbon during tank cycle startup. He doesn't not to do it ever. The rationale is to prevent accelerating the growth of heterotrophic bacteria, which grow much faster, from outcompeting the growth of the chemolithotrophic bacteria you are trying to get started.

I don’t actually know which type of bacteria are the most useful long term, but I appreciate the clarification. I don’t generally watch videos, and I also would not organic carbon dose during cycling, but perhaps more for reasons of lack of nutrients rather than a clear preference for nitrifying bacteria.