Uptaking only dkH

[MiZuboov]

Hi!
I have mixed reef and I observe my aquarium is uptaking only Carbonate hardness and I need every third day to increase dose on my Autodoser. Why it is so?
I would like to increase it to 8,5 dKh.
Uptaking of Calcium doesn't changed. It is stabled on 430
Mg is stabled on 1380
Another elements I'm in control with ICP-test every third week, it's ok.
The aquarium is 2 years old and growth of my corals is very moderate.
NO3 is about 25 ppm
PO4 is about 0,1 - 0,25 ppm.
Salinity 34.
Corals like Euphyllia and other die periodically, but rarely.
Main problem is very slow growth.
Any tips and recommendations would be helpful!
Thank you a lot!

 

[Randy Holmes-Farley Verified Community Expert]

What is the daily alk demand? When low, say 0.3 dKH per day, the balanced calcium demand (2 ppm per day) is very hard to see in the short term. Some alk demand also comes from rising nitrate.

I don’t see anything in what you wrote that would cause slow growth. Do you ever dose trace elements? Lighting and flow are good?

 

[Pod_01]

As mentioned by Randy it is difficult to measure Calcium and Mg consumption when there is low Alk consumption.
The consumption for Alk, Ca and Mg is as follow:

Alk 2.8 dKH
Calcium 18-20 ppm
Magnesium 0-2 ppm

My corals did show significant improvement once I started daily dosing trace elements. I use Tropic Marin A and K elements.
The same trace mix is in Tropic Marin All For Reef so that is another option.
I do keep the A and K elements dosage on the minimum, from my experience less works better.

 

[rishma]

The consumption for Alk, Ca and Mg is as follow:

Alk 2.8 dKH
Calcium 18-20 ppm
Magnesium 0-2 ppm

^this

Which is why don’t test calcium or magnesium except the an occasional ICP. I always dose calcium with alkalinity and I never assume one so consumed and the other is not.

 

[MiZuboov]

What is the daily alk demand? When low, say 0.3 dKH per day, the balanced calcium demand (2 ppm per day) is very hard to see in the short term. Some alk demand also comes from rising nitrate.

I don’t see anything in what you wrote that would cause slow growth. Do you ever dose trace elements? Lighting and flow are good?

After some calc I revealed some numbers: Calcium demand 3,3 ppm/day, dKh demand 0,3 ppm/day. That's almost normally balanced demand.. I have high nitrates, about 20, but recently measure got me about 10..
I'm dosing Iron every day 1ml from Red Sea, but ICP show me at 0 level. And Bioactive elements Red Sea D 1-2 ml 2x/week. Remaining additives looking on ICP I no need.
Lightning: Radeon 30 G6, flow is good :))

 

[rishma]

If I recall, when nitrate drops it contributes some alkalinity back to the water. I would not expect your actual consumption varies from the proportions @Pod_01 showed above. Perhaps the reduction in nitrate provides the balance of the alkalinity and/or minor test error. Pretty close either way.

 

[MiZuboov]

^this

Which is why don’t test calcium or magnesium except the an occasional ICP. I always dose calcium with alkalinity and I never assume one so consumed and the other is not.

You know, I would like to dose exactly as much as is consumed, but looking at reefing an awful lot of people I understand more and more AFR is really best solution. Allegedly you can't to dose only dKh if you have only dKh consumption you need to dose calcium and traces anymore. But why? I can't to understand this mechanic, but I will do it..))

 

[Rollnwthdatide]

As mentioned by Randy it is difficult to measure Calcium and Mg consumption when there is low Alk consumption.
The consumption for Alk, Ca and Mg is as follow:

Alk 2.8 dKH
Calcium 18-20 ppm
Magnesium 0-2 ppm

My corals did show significant improvement once I started daily dosing trace elements. I use Tropic Marin A and K elements.
The same trace mix is in Tropic Marin All For Reef so that is another option.
I do keep the A and K elements dosage on the minimum, from my experience less works better.

Do you also dose AFR along with the A and K elements?

 

[rishma]

@MiZuboov I think it would be a usual and temporary circumstance to have only dKH consumption. When people observe what they think is dKH only consumption it is often just calcium measurement issues. Calcium tests are much less reliable than alkalinity tests, in my experience.

I dose kalkwasser and AFR. They both provide alkalinity and calcium. AFR also provides magnesium and trace elements. They both provide a little bit of excess calcium vs what’s consumed, but it generally is not an issue.

 

[rishma]

@MiZuboov Calcifying organisms use alkalinity, calcium and magnesium in the proportions listed by @Pod_01. Coraline algae uses near the higher end of magnesium, corals utilize magnesium at the lower end of the range.

In a reef tank, these proportions will hold true. Once I learned this, my major element management became much easier.

 

[Pod_01]

Allegedly you can't to dose only dKh if you have only dKh consumption you need to dose calcium and traces anymore.

As mentioned you cannot have Alk consumption alone, but in low demand reef tank it may appear that is the case. The test kits we use are just not sensitive to detect the calcium and Mg use.
For corals to build skeleton they need both Alk and Calcium. Sometimes Calcium is replaced by Mg.
For corals to thrive they also require trace elements, some trace elements are essential and once they get used up corals will stagnate.
From my experience TM A and K elements works well to deal with trace elements, also what I find is that less seems to work better in my tank.

 

[Pod_01]

Do you also dose AFR along with the A and K elements?

You can, but AFR has A and K in it. When I used AFR I did experiment with extra A and K but it didn’t seem to provide benefit. It may help to dose extra A and K on new tank where AFR dose is small and trace elements are depleted.

If you have condition where trace elements are depleted and are limiting growth adding extra A and K will help, if your tank has enough trace elements adding A and K will not help. In that case the limitations may be P, N etc…

Right now I use TM Original Balling and I do add TM A and K at the minimum dose.

 

[MiZuboov]

It may help to dose extra A and K on new tank where AFR dose is small and trace elements are depleted.

Aren't Ca, dKh and traces consumed accordingly to each other?

 

[Randy Holmes-Farley Verified Community Expert]

I'm dosing Iron every day 1ml from Red Sea, but ICP show me at 0 level. And Bioactive elements Red Sea D 1-2 ml 2x/week.

What sort of ICP? Unless it is ICP-MS, it cannot detect natural levels of iron.

 

[Randy Holmes-Farley Verified Community Expert]

Aren't Ca, dKh and traces consumed accordingly to each other?

No. Think of bacteria, soft corals, and macroalgae. They take up plenty of trace elements, and zero alk and calcium.

 

[Rollnwthdatide]

You can, but AFR has A and K in it. When I used AFR I did experiment with extra A and K but it didn’t seem to provide benefit. It may help to dose extra A and K on new tank where AFR dose is small and trace elements are depleted.

If you have condition where trace elements are depleted and are limiting growth adding extra A and K will help, if your tank has enough trace elements adding A and K will not help. In that case the limitations may be P, N etc…

Right now I use TM Original Balling and I do add TM A and K at the minimum dose.

I currently use AFR but a very low intake as I only dose 6.7ml a day for a 50gal AIO. However, when I did a ICP test, I was low on most trace elements. I might dose the TM A and K and at a very low amount and see if that remedies until I start increasing my AFR dosage

 

[Randy Holmes-Farley Verified Community Expert]

I currently use AFR but a very low intake as I only dose 6.7ml a day for a 50gal AIO. However, when I did a ICP test, I was low on most trace elements. I might dose the TM A and K and at a very low amount and see if that remedies until I start increasing my AFR dosage

That is a fine strategy. I'm considering doing something similar in my tank. When alk demand is low, AFR will only add a low amount of trace elements. Maybe it is enough, and maybe not, depending on how many other organisms use trace elements and not alk/calcium. :)

 

[MiZuboov]

I currently use AFR but a very low intake as I only dose 6.7ml a day for a 50gal AIO. However, when I did a ICP test, I was low on most trace elements. I might dose the TM A and K and at a very low amount and see if that remedies until I start increasing my AFR dosage

Could you show your last ICP?

 

[MiZuboov]

What sort of ICP? Unless it is ICP-MS, it cannot detect natural levels of iron.

Our test ICP-MS measures 20-50 umg/l. I have <20 umg/l.

 

[skiergd011013]

Is there a set amount of alk per dose in afr? For example, if i know my tanks consumption is 0.7 dkh per day, what would be the daily afr dose? I only test alk. I test calcium once in a while with my hanna checker, and it is always over 400. Its a 20 gallon. Right now i just dose liquid baking soda at 0.7dkh a day, and change 3 gallons a week with reef crystals. My target is 9dkh. The dosing is keeping it close. Once or twice a week if i see it dipping slightly, ill do an extra correction dose to get it back to 9. I have a big bottle of afr that im considering trying. But everythings looking good so i dont know if a change is the right move.