Unusually high ALK (15.6)

[bluemon]

Hi everyone!

Been in the Hobby nearly 15 years now, and my current 125G is around 10 years old, so I like to think I know my way around water chemistry.

However, I do have to admit I am a lazy reefer and often times forgo testing the water if the corals look fine (and they do 99% of the time)

I did recently just get a second Maxima clam and to see how much calcium/ALK they would need, I decided to test my water, and had some shocking results.

The ALK was at 15.6; Everything in the tank looked fine (Tank is mostly LPS + few shrooms and softies + anemones and clams), probably thanks to the high nutrient setup I run (20ppm nitrates)

So I did a quick water change and I am posting this a day after the water change to check in and see what I could be doing.

The recent increase in Alkalinity was probably due to the calcium reactor outputting a bit too much so I stopped that running for a while while the corals consume the calcium and ALK.

The parameters are as follows (the highish pH concerns me a bit too, but may be a calibration issue):

Salinity: 1.024
ALK: 13.6 (checked with HANNA and Salifert)
Calcium: 430 ppm
Magnesium: 1150 ppm
Nitrate: 25 ppm
pH: 8.5-8.6

A newly mixed in water with my mix is around 10 ALK.

What is the best way I could go about with these parameters?
I did notice the meat corals looking slightly better maybe after lowering my ALK from 15.6, but honestly, they looked fine before and were expanding and eating well. The Clams looked perfectly fine as well as well as my Euphyllia.

My plan of attack was to just let the tank "consume" ALK while I have my calcium reactor stopped for now, but I do worry that the Calcium and Mg levels are quite normal compared to the Alkalinity. And also doing another 20% water change while maybe turning on my Calcium reactor just a bit for steady calcium/MG levels

I know high ALK levels alone are not too much of a red flag especially in a high nutrient system, but just wanted to check.

Thanks everyone.

Again, the tank looks better than ever, and this isn't too much of an emergency, but I have never had ALK above 11 in my 15 years of reefkeeping so I was a bit concerned

 

[Lavey29]

Your magnesium is low. This is the buffer between alk and calcium to prevent precipitation. Yes alk needs to come down slowly.

 

[Reginald Reefer III]

Your magnesium is low. This is the buffer between alk and calcium to prevent precipitation. Yes alk needs to come down slowly.

Slowly is the key word.

 

[bluemon]

Your magnesium is low. This is the buffer between alk and calcium to prevent precipitation. Yes alk needs to come down slowly.

Nice to know. I did notice it was a bit lower than the recommended levels. I do have to run my calcium reactor to increase my Mag levels as I have magnesium chips in there. Think it would be wise to fire that up again? maybe while doing another water change?

Slowly is the key word.

Of course. I think a water change usually drops it by 1dKH, and I would do it every two days.

 

[Lavey29]

Nice to know. I did notice it was a bit lower than the recommended levels. I do have to run my calcium reactor to increase my Mag levels as I have magnesium chips in there. Think it would be wise to fire that up again? maybe while doing another water change?


Of course. I think a water change usually drops it by 1dKH, and I would do it every two days.

Or just dose magnesium it's easy to do by hand

 

[Randy Holmes-Farley Verified Community Expert]

Mag may not be accurate. I’d at least test the new salt water before believing it.

The salinity is also low, which will raise both calcium and magnesium if you raise it.

 

[bluemon]

Mag may not be accurate. I’d at least test the new salt water before believing it.

The salinity is also low, which will raise both calcium and magnesium if you raise it.

I’ll whip up a new mix tonight and see where the numbers are.

And I’ll try to find if I have anything to dose Mag with too if it comes down to that.

 

[bluemon]

Found half the culprit. Seems this batch of Red Sea pro salt had unusually high ALK (I know it’s usually a bit higher than other salts but it seems it is higher still)

As the newly mixed salt measured at

11.1 alk
1290 Mg
440 Ca

Might have to look for a new salt mix as I run a calcium reactor anyways