ALK / Ca consumption 'ratio'?

[TomSerious]

Hello!
I am quite new to the reefing hobby and started my first reef tank about 3 months ago (done Freshwater for 2 years).

Now I can't seem to find any information (of course every tank is different) on an approximate consumption ratio of Alk and Ca.

My current Values are as following:
Alk 7.6 dKH (would like to increase to 9 dKH over time)
Ca 435 ppm
Mg ~ 1400 ppm

I am using the Hanna Checkers for Ca and Alk, Red Sea for Mg.
Since I work with laboratory equipment, I am confident that I execute the Ca Hanna Test pretty precisely and if I do 2-3 tests back to back, I get pretty much the same results.

I have the tank heavily stocked with coral (LPS and SPS mixed) and everything is growing nicely.
The tank is an Aqua Medic Armatus 300 XD (a bit bigger than a 60 gal cube, I guess)


Now... my Alk consumption seems to be high but reasonable (about 1.6 in 24h)
But i don't understand my Ca... at first it didn't really budge much and now it's, I think at least, pretty high (19 ppm in 24h!)??

The only number/ratio I heard was in some BRS video of "1 Alk and 7 Ca per day" and to that, my "ratio" seems pretty off.

Do these numbers seem reasonable to you?
Or is there something wrong?

Thank you very much in advance!


Regards,
Thomas

 

[chipmunkofdoom2]

Hello!
I am quite new to the reefing hobby and started my first reef tank about 3 months ago (done Freshwater for 2 years).

Now I can't seem to find any information (of course every tank is different) on an approximate consumption ratio of Alk and Ca.

My current Values are as following:
Alk 7.6 dKH (would like to increase to 9 dKH over time)
Ca 435 ppm
Mg ~ 1400 ppm

I am using the Hanna Checkers for Ca and Alk, Red Sea for Mg.
Since I work with laboratory equipment, I am confident that I execute the Ca Hanna Test pretty precisely and if I do 2-3 tests back to back, I get pretty much the same results.

I have the tank heavily stocked with coral (LPS and SPS mixed) and everything is growing nicely.
The tank is an Aqua Medic Armatus 300 XD (a bit bigger than a 60 gal cube, I guess)


Now... my Alk consumption seems to be high but reasonable (about 1.6 in 24h)
But i don't understand my Ca... at first it didn't really budge much and now it's, I think at least, pretty high (19 ppm in 24h!)??

The only number/ratio I heard was in some BRS video of "1 Alk and 7 Ca per day" and to that, my "ratio" seems pretty off.

Do these numbers seem reasonable to you?
Or is there something wrong?

Thank you very much in advance!


Regards,
Thomas

This is likely calcium testing error. This happens quite often. A hobbyists measures a decrease in alkalinity, but not calcium. They ask if they should only be dosing alkalinity since calcium is not decreasing. If alkalinity is decreasing, calcium almost always is as well. It just may take time to measure a calcium decrease because the consumption is comparatively low and the test kits we use aren't perfect. The Hanna Calcium Checker is especially imperfect because of the dilution required.

What you are seeing fits this description. Your alkalinity is decreasing daily, and eventually, after calcium has decreased enough to be detected, a drop in calcium is measured.

If you are dosing to maintain alkalinity, you should be dosing the same amount of calcium additive daily, provided your additive is balanced. Most are. If you would like to raise your alkalinity to a new setpoint, dose a little bit more of your alkalinity supplement daily until your values are where you want them. Then, revert to dosing the same amount of each two-part to maintain the new levels.

 

[CaptainCooke]

This is likely calcium testing error. This happens quite often. A hobbyists measures a decrease in alkalinity, but not calcium. They ask if they should only be dosing alkalinity since calcium is not decreasing. If alkalinity is decreasing, calcium almost always is as well. It just may take time to measure a calcium decrease because the consumption is comparatively low and the test kits we use aren't perfect. The Hanna Calcium Checker is especially imperfect because of the dilution required.

What you are seeing fits this description. Your alkalinity is decreasing daily, and eventually, after calcium has decreased enough to be detected, a drop in calcium is measured.

If you are dosing to maintain alkalinity, you should be dosing the same amount of calcium additive daily, provided your additive is balanced. Most are. If you would like to raise your alkalinity to a new setpoint, dose a little bit more of your alkalinity supplement daily until your values are where you want them. Then, revert to dosing the same amount of each two-part to maintain the new levels.

Beat me to it! I was just writing the same!

 

[TomSerious]

This is likely calcium testing error. This happens quite often. A hobbyists measures a decrease in alkalinity, but not calcium. They ask if they should only be dosing alkalinity since calcium is not decreasing. If alkalinity is decreasing, calcium almost always is as well. It just may take time to measure a calcium decrease because the consumption is comparatively low and the test kits we use aren't perfect. The Hanna Calcium Checker is especially imperfect because of the dilution required.

What you are seeing fits this description. Your alkalinity is decreasing daily, and eventually, after calcium has decreased enough to be detected, a drop in calcium is measured.

If you are dosing to maintain alkalinity, you should be dosing the same amount of calcium additive daily, provided your additive is balanced. Most are. If you would like to raise your alkalinity to a new setpoint, dose a little bit more of your alkalinity supplement daily until your values are where you want them. Then, revert to dosing the same amount of each two-part to maintain the new levels.

Thanks for your reply!

But currently I am measuring daily and I see a daily drop in calcium which corresponds to about 19ppm daily.


Is 19ppm per day a normal value?


I will check again today (I always check at 21:00 CEST)

I am using the Balling Light "system" of Fauna Marin > I think I have to dose about 4 x as much Alk as I dose Ca.
Which it doesn't 100% but maybe close enough.