Calcium dropping while alk and mag stable

[jacob.morgan78]

Its taken about a month but my calcium has dropped from 420 to 360. My alk is stable at 10 dkh and mag is stable at 1360. I use brs two part and have the amount of calcium and alkalinity being dosed (by pumps) in the exact same amount.

Any ideas? Should I just dose more calcium than alk daily? Or just supplement an amount of calcium needed found by by testing once a month?

Thanks for any guidance anyone can offer!

 

[Randy Holmes-Farley]

What salt mix are you using for water changes?

It may be low in calcium, but in any case, just up the calcium dose a bit, or once in a while, make a one time boost.

 

[jacob.morgan78]

Gradually changing from tropic Marin pro reef to instant ocean reef crystals. However, I haven't done my water change yet this month...

I think the occasional boost will be the way I go. I was very hesitant though because I thought they stayed in a more constant ratio naturally... I read your reef alchemy article but nothing seemed to fit my situation.

Any ideas on why this is like this? I'm using ati tests and tested twice to double check. This is the second time recently that my calcium has dropped. I have a fairly new tank, a little less than a year with mostly frags of mixed reef "stuff" so I'm expecting to need to up my dosing but thought I would need to raise my alk dosing too...

I'm also a little concerned about growth rate... Will doing the occasional boost slow growth much? I'm not overly concerned with this but fast growh is always nice!

Thanks so much for your quick feedback. I have a lot of respect for what you say!

 

[bertoni]

Hmm, the most likely possible causes that come to mind:

1) a slight mismatch on the strength of the solutions
2) a stealthy alkalinity addition, like tap water or pH buffers

Even the low calcium number should be fine for plenty of growth.

 

[Randy Holmes-Farley]

I agree. Calcium has to get pretty low to be limiting to hard coral growth.

 

[jacob.morgan78]

Thank you!

 

[SpinyReef]

Did you check your dosing pump to make sure its doing its job? I had problems with mine recently and the calcium dropped to 220ppm before I figured it out. At that point growth had stopped and some acros were starting to burn(dissolve?) at the tips. You can raise calcium 25ppm per day safely

 

[Randy Holmes-Farley]

Yes, one should not assume that dosing pumps always dose what they are claimed to, and those number may change over time as the tubing gets stretched and distorted (if it is a peristaltic pump).

 

[jacob.morgan78]

I've been keeping an eye on it... they seem to be working fine. One way I know is that there is always a spike in pH at the time when it's supposed to dose. I'm not sure if the calcium AND alkalinity cause a spike in pH or if it's just one. Maybe I'll run the tubing into a beaker tonight to check...

Thanks for all the help!

 

[ek9vboi]

Same thing happened to me as well, my tank is a little over a month old now but I assume the calcium take up was from the development of coralline algae on my rocks. Since then I've been "chasing" numbers and things are a lot more stable now. It's more of my alk that drop then anythings so I'm keeping an eye out for that. Dosing equal amounts for now to see what happens and if anything I'll be dosing more of what's needed to make up the difference. I'm also looking into using kalkwasser via ATO so I would have to dose less and keep levels sustained.

 

[Randy Holmes-Farley]

I've been keeping an eye on it... they seem to be working fine. One way I know is that there is always a spike in pH at the time when it's supposed to dose. I'm not sure if the calcium AND alkalinity cause a spike in pH or if it's just one. Maybe I'll run the tubing into a beaker tonight to check...

Thanks for all the help!

Well, only the alk part has an effect on pH, and even if you dosed half as much or twice as much as expected, you'd still see some pH effect. That is the concern with inexpensive dosing pumps over time: changing amounts.