Calcium won’t go down

[Sprinting]

Hello,

A few months ago I noticed my calcium level was about 600. Even after months of not dosing any calcium and doing water changes every few weeks my calcium is still at 475.

Alk was 7.9 last I checked but I dose about 10 ml of Red Sea alk daily

magnesium has been at 1350 whenever I check it.

The calcium thing and life made me kind of neglect my tank for a bit and a few weeks ago, I had my nitrates climb up to about 40 which caused quite a few sps to die.

Everything seems fairly stable again but this calcium thing is really making me scratch my head and I cant help but wonder if it’s affecting the overall health of my tank. I have about 20 fish, feed LRS daily and a variety of corals in a 75 gallon. Numerous mature colonies but the sps are pretty much gone now.

Thanks for any input!

 

[Lavey29]

475 is not bad but if you raise your alk a bit to like 8.5 it may drop down to 400 range?

 

[vetteguy53081]

Increase alk a little. In calcium’s case, it is connected with alkalinity levels. As calcium rises, alkalinity levels tend to drop. At the same time, an increase in alkalinity can decrease calcium. If your calcium levels are too high in your reef aquarium, you run the risk of your alkalinity is too low.
The problem with this is that it affects the buffering capabilities of the water, which in turn affects the pH levels.

 

[Sprinting]

Thanks for the input! My alk was running at 10 for the last few months but my reservoir recently ran out so I just filled it. Even while it was higher my calcium would coast at 500 for a long time and it didn’t seem to take the calcium down. Is there any reason why I’m adding so much alk than calcium or does that happen? Only because it’s been elevated for months.

 

[Randy Holmes-Farley Verified Community Expert]

IMO, there's no reason to do anything to try to lower calcium that is at 475 ppm.

You aren't adding very much alk (less than 0.4 dKH per day), so one would not expect much decline in calcium.

Ever measure the calcium in your salt mix with the same kit?

Accumulating nitrate depletes alk and that may be the source of your alk demand, not calcification.

 

[Lavey29]

Thanks for the input! My alk was running at 10 for the last few months but my reservoir recently ran out so I just filled it. Even while it was higher my calcium would coast at 500 for a long time and it didn’t seem to take the calcium down. Is there any reason why I’m adding so much alk than calcium or does that happen? Only because it’s been elevated for months.

I recently set up my doser and it is on a 2 to 1 ratio for alk and cal. My cal number just does not fluctuate as much as the alk number. I know 1 to 1 is ideal but each systems demands may be unique.

 

[Sprinting]

IMO, there's no reason to do anything to try to lower calcium that is at 475 ppm.

You aren't adding very much alk (less than 0.4 dKH per day), so one would not expect much decline in calcium.

Ever measure the calcium in your salt mix with the same kit?

Accumulating nitrate depletes alk and that may be the source of your alk demand, not calcification.

I’ll have to measure my calcium for a new batch of salt. Lol I really hate testing but I should’ve started there.

If I understand you correctly, you’re saying my tank is using alkalinity to remove nitrates? That sure would explain a lot.

I appreciate the reassurance from everyone that 475 is nothing to freak out about. I think it got to 600 for a bit when I was dosing calcium because the guy at my local store was adamant that I had to dose equal parts. I’ll just plan on keeping a better eye on my nitrates and add some more alk moving forward.

 

[Randy Holmes-Farley Verified Community Expert]

I’ll have to measure my calcium for a new batch of salt. Lol I really hate testing but I should’ve started there.

If I understand you correctly, you’re saying my tank is using alkalinity to remove nitrates? That sure would explain a lot.

I appreciate the reassurance from everyone that 475 is nothing to freak out about. I think it got to 600 for a bit when I was dosing calcium because the guy at my local store was adamant that I had to dose equal parts. I’ll just plan on keeping a better eye on my nitrates and add some more alk moving forward.

No, I'm saying production of nitrate depletes alk, so if nitrate is rising (not stable, regardless of level, but actually rising) then alkalinity declines for that reason.

Consumption of nitrate gives the alk back. That's why stable readings (production = consumption) are not going to impact alk.

For calcium, I recommend 400-550 ppm.

 

[Randy Holmes-Farley Verified Community Expert]

I recently set up my doser and it is on a 2 to 1 ratio for alk and cal. My cal number just does not fluctuate as much as the alk number. I know 1 to 1 is ideal but each systems demands may be unique.

Calcium is always far more stable than alk because seawater has a relative big reservoir of calcium and little alk.

As to the 2:1, what exactly are you dosing?

Many folks making this sort of unbalanced demand claim discover that what they are dosing was never designed for 1:1 dosing, or their pumps are not matched well.

In reality, unless demand is low where minor impacts to alk become dominating (mostly water changes or nitrate issues), most reefs will use alk and calcium at fairly close to 1:1.

In very telling, IMO, that rarely do folks actually using forced 1:1 products (like kalkwasser or a CaCO3/CO2 reactor) claim that their tanks needs more alk or more calcium every day. Deviations from balance are slow building and are for well understood reasons (such as kalkwasser known to have a slight excess of calcium delivery over time).

 

[Lavey29]

Calcium is always far more stable than alk because seawater has a relative big reservoir of calcium and little alk.

As to the 2:1, what exactly are you dosing?

Many folks making this sort of unbalanced demand claim discover that what they are dosing was never designed for 1:1 dosing, or their pumps are not matched well.

In reality, unless demand is low where minor impacts to alk become dominating (mostly water changes or nitrate issues), most reefs will use alk and calcium at fairly close to 1:1.

In very telling, IMO, that rarely do folks actually using forced 1:1 products (like kalkwasser or a CaCO3/CO2 reactor) claim that their tanks needs more alk or more calcium every day. Deviations from balance are slow building and are for well understood reasons (such as kalkwasser known to have a slight excess of calcium delivery over time).

I'm still trying to dial in the exact ratio but using bionic 2 part. Early on my tank seemed to be using alk but no calcium and weekly water changes compensated for it. Then I went every 2 weeks on water changes and was hand dosing alk but calcium stayed relatively unchanged. Now I have a lot of corals and coraline so alk consumption has increased and calcium as well but they do not seem to deplete at the same daily amount. I currently dose 16ml of bionic alk which is stabil at 9dkh. I dose 8ml of calcium which seems to stay in the 450 range now consistently. I use red sea coral pro salt with 10g water change every 2 weeks on an 80g total system.

 

[Randy Holmes-Farley Verified Community Expert]

I'm still trying to dial in the exact ratio but using bionic 2 part. Early on my tank seemed to be using alk but no calcium and weekly water changes compensated for it. Then I went every 2 weeks on water changes and was hand dosing alk but calcium stayed relatively unchanged. Now I have a lot of corals and coraline so alk consumption has increased and calcium as well but they do not seem to deplete at the same daily amount. I currently dose 16ml of bionic alk which is stabil at 9dkh. I dose 8ml of calcium which seems to stay in the 450 range now consistently. I use red sea coral pro salt with 10g water change every 2 weeks on an 80g total system.

That's about 0.4 dKH a day, which for calcification would require about 2.7 ppm of calcium a day. You are dosing about 1.6 ppm a day, for a shortfall of about 1.1 ppm a day.

Water changes and other minor factors might make that difference.

 

[Lavey29]

That's about 0.4 dKH a day, which for calcification would require about 2.7 ppm of calcium a day. You are dosing about 1.6 ppm a day, for a shortfall of about 1.1 ppm a day.

Water changes and other minor factors might make that difference.

I agree with your numbers but when I tried the 1 to 1 ratio my calcium climbed to 497 and when I cut the calcium dose in half it is now 470 this morning. I anticipate as I get more calcium demand from coraline and coral growth that my ratio will edge back towards 1 to 1.

Does this seem like a reasonable expectation?

 

[Randy Holmes-Farley Verified Community Expert]

I agree with your numbers but when I tried the 1 to 1 ratio my calcium climbed to 497 and when I cut the calcium dose in half it is now 470 this morning. I anticipate as I get more calcium demand from coraline and coral growth that my ratio will edge back towards 1 to 1.

Does this seem like a reasonable expectation?

More calcification of any type will drive it toward 1:1, yes.

 

[Lavey29]

OP sorry for getting slightly off topic in your thread but as you can see we all deal with parameters sometimes that are slightly off or way off. In your case, I think we can all agree that your calcium number is not that bad and would not negatively impact your tank at that level. Seems like raising the alk slightly would help lower it or even better add a bunch of cool new corals to increase calcium demand in your tank too.