Alkalinity consumption drop - Not sure what that means

[stlamarc]

Hi gurus,

I want to ask the experts on this forum what a sudden drop in Alkalinity consumption could mean. The tank has been running for about 10-12 months and I understand things are still not super stable, but I'm just concerned this is something I need to pay more attention or if it's a sign of something going wrong.

The Alkalinity and Calcium dosing was relatively equal at about 70ml/day in my 110 gallons system for several months. There were no significant change in corals and all looked happy, but the Alkalinity consumption dropped to about 1ml/day for the last 1-2 months, while the calcium stayed about the same and actually increased a little. I'm now dosing 100ml/day of calcium to maintain about 420ppm. My nitrate increased from 3-5 to about 10 during that period as well.

Everything looks very healthy and coral colonies are still growing at a good pace. I'm just concerned the tank is trying to tell me something and I have no clue what is causing this sudden drop of Alkalinity consumption. Could this simply be part of the system going through another phase of development and there's nothing to worry about??

Is this a common thing in maturing systems?

Thank you in advance.

 

[KrisReef]

If this was a dry rock start I would guess that the rock has "matured" = alk deposition spots in the rock are now "full" and the only consumption is from the corals?

 

[stlamarc]

If this was a dry rock start I would guess that the rock has "matured" = alk deposition spots in the rock are now "full" and the only consumption is from the corals?

This helps thank you. But why would the Calcium consumption is high compared to Alkalinity. 1/100 ratio currently.

 

[billyocean]

Depends on how many and what type of coral also. I have a heavy acro tank that consumes almost twice as much alk as cal.

 

[biom]

Hi gurus,

I want to ask the experts on this forum what a sudden drop in Alkalinity consumption could mean. The tank has been running for about 10-12 months and I understand things are still not super stable, but I'm just concerned this is something I need to pay more attention or if it's a sign of something going wrong.

The Alkalinity and Calcium dosing was relatively equal at about 70ml/day in my 110 gallons system for several months. There were no significant change in corals and all looked happy, but the Alkalinity consumption dropped to about 1ml/day for the last 1-2 months, while the calcium stayed about the same and actually increased a little. I'm now dosing 100ml/day of calcium to maintain about 420ppm. My nitrate increased from 3-5 to about 10 during that period as well.

Everything looks very healthy and coral colonies are still growing at a good pace. I'm just concerned the tank is trying to tell me something and I have no clue what is causing this sudden drop of Alkalinity consumption. Could this simply be part of the system going through another phase of development and there's nothing to worry about??

Is this a common thing in maturing systems?

Thank you in advance.

Not a guru or expert here but I am not aware of a process in the reef tank that will consume only calcium. Doesn't matter if it is precipitation or calcification it will require equal amounts of calcium and alkalinity. Which means the alkalinity part should come from somewhere else if you are not dosing it. And if it is not testing/dosing error, the additional alkalinity could came from nitrate assimilation/denitrification but in your case you have nitrate raising so I doubt it is like this. It could come from tap/spring water if such is used for top off.

 

[biom]

Depends on how many and what type of coral also. I have a heavy acro tank that consumes almost twice as much alk as cal.

Not really depends on number or species of corals. All species of "stony" corals will consume equal parts of calcium and alkalinity for calcification. The same is valid for abiotic precipitation of calcium carbonate. If there is more alkalinity consumption in your tank this is probably because there are other processes happening in parallel that also require alkalinity as nitrification/ assimilation of ammonia for example or it is testing/dosing error.

 

[biom]

If this was a dry rock start I would guess that the rock has "matured" = alk deposition spots in the rock are now "full" and the only consumption is from the corals?

not sure what "alk deposition spots" means. But if it means that uncured artificial rock could leach alkalinity then the process would be exactly opposite - there will be less demand for alkalinity in the beginning and slowly equalize with calcium dosing when the rock is mature.

 

[19Mateo83]

Are your magnesium levels in your target range?

 

[Randy Holmes-Farley Verified Community Expert]

This helps thank you. But why would the Calcium consumption is high compared to Alkalinity. 1/100 ratio currently.

What does that mean?

There is no processes that uses more than 20 ppm of calcium for each 2.8 dKH of alk, but you may be adding alk in other ways.

 

[KrisReef]

not sure what "alk deposition spots" means. But if it means that uncured artificial rock could leach alkalinity then the process would be exactly opposite - there will be less demand for alkalinity in the beginning and slowly equalize with calcium dosing when the rock is mature.

Chemical bonding locations in rock attract alk deposition and remove alk from the water until filled.

The element that can be released (and is sometimes seen) is phosphate from dry or old tank rocks. Both instances have been observed/reported in postings on this site.

 

[biom]

Chemical bonding locations in rock attract alk deposition and remove alk from the water until filled.

Alkalinity is just buffering capacity of the water it is not element or chemical. That is why I am not sure I understand how it can fill specific deposition spots and how is attracted to them.
In the past there were artificial rocks made by white cement which is very basic pH 11-13 and can raise alkalinity if not cured.

Phosphate binding to calcium carbonate is different process.

 

[KrisReef]

Well you got me, my chemical understanding of what is going on in salt water ionic interactions is very fuzzy and my description of what/how/ why etc is indicative of my lack of precision in discussing what happens.
RHF is the best source I admire and struggle to grasp but here’s a ripped clip from his work that I lamely site here to help explain myself in this thread:

From HERE

Chemical Species	Relative Contribution To Alkalinity
HCO3– (bicarbonate)	89.8
CO3— (carbonate)	6.7
B(OH)4– (borate)	2.9
SiO(OH)3– (silicate)	0.2
MgOH+ (magnesium monohydroxylate)	0.1
OH– (hydroxide)	0.1
HPO4— and PO4— (phosphate)	0.1

Other species can also contribute measurably to alkalinity in seawater in certain situations, such as anoxic regions. These would include NH4+ and HS– .

——-—

So, the action of the “Alk” between water and dry rock bonding sites is mostly involving carbonate and bicarbonate ions that are dissolved in salt water in our tanks. The chemical reaction with the dry rock removes them from the water and “uses” up alkalinity (what we measure) in the process.

Hat tip @Randy Holmes-Farley , he’s often on here explaining stuff or clarifying stuff that I can’t really properly explain myself.
Hth.

 

[Randy Holmes-Farley Verified Community Expert]

It’s carbonate that binds. The idea is that calcium carbonate precipitates onto fresh bare calcium carbonate. Both calcium and carbonate are binding, but the calcium change is much harder too see against the much higher calcium background in seawater.

 

[biom]

It’s carbonate that binds. The idea is that calcium carbonate precipitates onto fresh bare calcium carbonate. Both calcium and carbonate are binding, but the calcium change is much harder too see against the much higher calcium background in seawater.

Yep and this is still precipitation and will not consume more alkalinity than calcium and cannot explain OP alkalinity issues.

 

[Dan_P]

Hi gurus,

I want to ask the experts on this forum what a sudden drop in Alkalinity consumption could mean. The tank has been running for about 10-12 months and I understand things are still not super stable, but I'm just concerned this is something I need to pay more attention or if it's a sign of something going wrong.

The Alkalinity and Calcium dosing was relatively equal at about 70ml/day in my 110 gallons system for several months. There were no significant change in corals and all looked happy, but the Alkalinity consumption dropped to about 1ml/day for the last 1-2 months, while the calcium stayed about the same and actually increased a little. I'm now dosing 100ml/day of calcium to maintain about 420ppm. My nitrate increased from 3-5 to about 10 during that period as well.

Everything looks very healthy and coral colonies are still growing at a good pace. I'm just concerned the tank is trying to tell me something and I have no clue what is causing this sudden drop of Alkalinity consumption. Could this simply be part of the system going through another phase of development and there's nothing to worry about??

Is this a common thing in maturing systems?

Thank you in advance.

Just to clarify, you were adding a calcium supplement and an alkalinity supplement, both at a 70 mL each day for 2-4 months, then 1-2 months ago, the alkalinity supplement addition per day was 1 mL.

Questions

How do you determine the amount of supplement to add each day?

What is the concentration or strength of each supplement?

 

[stlamarc]

Just to clarify, you were adding a calcium supplement and an alkalinity supplement, both at a 70 mL each day for 2-4 months, then 1-2 months ago, the alkalinity supplement addition per day was 1 mL.

Questions

How do you determine the amount of supplement to add each day?

What is the concentration or strength of each supplement?

I'm using the BRS bulk pharma 2 part using Soda Ash and Calcium Chloride pouches. You guys are way above my head with all the chemistry explanations. I'm just trying to understand if this is normal and If I need to worry about something happening in my tank that I should be aware of. Everything looks good and growing normally from what I can tell. Coral colonies are looking great. I was dosing with a dosing head the same amount each day to maintain my levels of Kh and Calcium. I"ve checked the dosing head, and it's also dosing the right amount. my Mag is also ok at around 1370 and stable.

I agree with you all saying that Alkalinity and Calcium should be dosed in about equal amounts, but that's why I'm asking if anyone understands what could be happening here with my system.

 

[stlamarc]

It’s carbonate that binds. The idea is that calcium carbonate precipitates onto fresh bare calcium carbonate. Both calcium and carbonate are binding, but the calcium change is much harder too see against the much higher calcium background in seawater.

I would like to revive this conversation because now my situation with Alkalinity is evolving to high Alkalinity in my tank. I tested 12 dkh tonight. Calcium is 360 and Nitrate is at 10ppm. PH is 8.0

Since I've completely stopped dosing Soda Ash 7 days ago. I CANNOT comprehend how my alkalinity keeps climbing.
What could be increasing Alkalinity without dosing anything other than Calcium Chloride. Now I'm debating having to dose Vinegar to reduce the alkalinity slowly back down to 9.

I need some serious advice guys. I'm a bit at a loss with this one. I'm not dosing anything else to this tank. at this point and the Alkalinity is climbing.

 

[Randy Holmes-Farley Verified Community Expert]

I would like to revive this conversation because now my situation with Alkalinity is evolving to high Alkalinity in my tank. I tested 12 dkh tonight. Calcium is 360 and Nitrate is at 10ppm. PH is 8.0

Since I've completely stopped dosing Soda Ash 7 days ago. I CANNOT comprehend how my alkalinity keeps climbing.
What could be increasing Alkalinity without dosing anything other than Calcium Chloride. Now I'm debating having to dose Vinegar to reduce the alkalinity slowly back down to 9.

I need some serious advice guys. I'm a bit at a loss with this one. I'm not dosing anything else to this tank. at this point and the Alkalinity is climbing.

Vinegar will not effectively reduce alkalinity.

How are you measuring alkalinity and do you know it is accurate?

What was it 7 days ago when you stopped dosing?

 

[stlamarc]

Vinegar will not effectively reduce alkalinity.

How are you measuring alkalinity and do you know it is accurate?

What was it 7 days ago when you stopped dosing?

Thank you so much for the reply. I'm very confused with what is going on here. But to answer your question it was at 10.3 dkh exactly 7 days ago when I stopped the dosing head for Soda Ash. Calcium is still running but Calcium is slowly going down at 360. I assume the increase in Alkalinity is lowering my Calcium, but that's only my assumption.

I'm using a HANA checker and my test is accurate for my other reef tank. I've also opened a new reagent to make sure and it's testing the same at 12 dkh. I'm sending a sample of water for ICP analysis today.

I was going to do a 25% water change today to try to control the Alkalinity level, but I just can't comprehend what could be increasing my Alkalinity like that. This is really far fetch, but all I can think of that changed a few months ago is that I started washing my filter socks with bleach and then letting them dry completely before reusing them. I'm not dosing any other chemicals to this tank.

 

[Randy Holmes-Farley Verified Community Expert]

Thank you so much for the reply. I'm very confused with what is going on here. But to answer your question it was at 10.3 dkh exactly 7 days ago when I stopped the dosing head for Soda Ash. Calcium is still running but Calcium is slowly going down at 360. I assume the increase in Alkalinity is lowering my Calcium, but that's only my assumption.

I'm using a HANA checker and my test is accurate for my other reef tank. I've also opened a new reagent to make sure and it's testing the same at 12 dkh. I'm sending a sample of water for ICP analysis today.

I was going to do a 25% water change today to try to control the Alkalinity level, but I just can't comprehend what could be increasing my Alkalinity like that. This is really far fetch, but all I can think of that changed a few months ago is that I started washing my filter socks with bleach and then letting them dry completely before reusing them. I'm not dosing any other chemicals to this tank.

Top off water is what?

Is nitrate declining or being dosed?