Alkalinity Consumption

[Reefer1978]

I can't figure out what's consuming my Alk as I am lightly stocked. Tank has 200g of water (240 - rock / sand, etc). First let me start with the measurements:

Alk: 6.2
Cal: 390
Mag: 1290

I am dosing Kalkwasser, through Avast Marine K2, topped off every 2 weeks. 10l per day (max evaporation reached). I have some SPS frags, all not doing well and not growing, few mushrooms, 10 large snails. Barely any visible coraline.

Can't figure out why I can't seem to raise parameters any further. I should also add I am dosing Phyto daily.

 

[Randy Holmes-Farley Verified Community Expert]

How are you measuring alk?

 

[Reefer1978]

How are you measuring alk?

Confirmed with both Aquaforest and Red Sea test kits.

 

[Randy Holmes-Farley Verified Community Expert]

Have you measured the potency of the reactor effluent? Many are far from saturated kalk.

 

[rishma]

Have you measured the potency of the reactor effluent? Many are far from saturated kalk.

How would one measure potency? Other than conductivity

 

[Reefer1978]

Have you measured the potency of the reactor effluent? Many are far from saturated kalk.

I have not, but it's mixing 24/7 with RODI, would there be a reason why it's not fully saturated?

 

[rishma]

I have not, but it's mixing 24/7 with RODI, would there be a reason why it's not fully saturated?

For reasons I don’t fully understand, Kalk reactors sometimes don’t work as well or as consistently as they should in theory. That’s the reason I just mix a fully saturated reservoir and dose from there. Guarantees consistency.

 

[Reefer1978]

For reasons I don’t fully understand, Kalk reactors sometimes don’t work as well or as consistently as they should in theory. That’s the reason I just mix a fully saturated reservoir and dose from there. Guarantees consistency.

I haven’t see any threads mentioning that with stirring reactors

 

[rishma]

I haven’t see any threads mentioning that with stirring reactors

I have and I measured with it with my own years ago. People are quite pleased with them. They are handy and the Avast seems like a nice one. Before you chase other explanations for alkalinity consumption I think it’s a good idea to check potency as Randy suggested. I don’t know how without a conductivity meter. If you have a conductivity probe the saturated Kalk should be about ~10.3mS/cm. It depends on temperature and I usually find my saturated Kalk a little lower than that but if your effluent from the reactor is much below that it’s not saturated.

 

[Reefer1978]

I have and I measured with it with my own years ago. People are quite pleased with them. They are handy and the Avast seems like a nice one. Before you chase other explanations for alkalinity consumption I think it’s a good idea to check potency as Randy suggested. I don’t know how without a conductivity meter. If you have a conductivity probe the saturated Kalk should be about ~10.3mS/cm. It depends on temperature and I usually find my saturated Kalk a little lower than that but if your effluent from the reactor is much below that it’s not saturated.

I can only measure Ph.

 

[rishma]

I can only measure Ph.

That won’t help much. It will be in the 12’s over a wide range of potency

 

[Randy Holmes-Farley Verified Community Expert]

How would one measure potency? Other than conductivity

Diluted alk or calcium, or by pH comparison to actual saturated kalk.

 

[Randy Holmes-Farley Verified Community Expert]

Make saturated kalk (say, 2 teaspoons in a cup of ro/di) and compare it to the effluent. We can convert the pH difference into a potency.

 

[rishma]

Make saturated kalk (say, 2 teaspoons in a cup of ro/di) and compare it to the effluent. We can convert the pH difference into a potency.

Brilliant :)

 

[Reefer1978]

Make saturated kalk (say, 2 teaspoons in a cup of ro/di) and compare it to the effluent. We can convert the pH difference into a potency.

@Randy Holmes-Farley for the new saturated kalk, do you mix it and then let it settle?

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley for the new saturated kalk, do you mix it and then let it settle?

Settling or not won’t impact a pH measurement.

The potency is close to 10^(delta pH).

So a 0.1 pH difference is about a 26% drop in potency (actually a little bit more of a drop for very nitty gritty chemical reasons).

 

[rishma]

Very curious what measurements you get when testing against saturated kalk

 

[Reefer1978]

I am going to perform the test and revert back guys. Thank you!!