Calcium and Magnesium increasing without dosing?!

[barrybigbum]

Hi all,

I've kept a reef tank for nearly 3 years. I upgraded just before Christmas to a custom built L shape which holds 725 litres (192 us gallons) of water. I set it up with new rock (aquaroche), new sand (aragonite - not live) and Natural Sea Water. I had 4 x mantis bio blocks and live rock in my sump which I transferred over to the new tank.

I didn't dose in my previous tank, mainly because it wasn't required until just before I upgraded. For the new tank I wanted to dose from the start as I planned on increasing my amount of corals with the extra space available.

I'm in the UK and looked in to different options and eventually settled on Oceamo Duo.

Initially I was testing daily and dosing the suggested amount by the distributor here in the UK. Levels were good but then started to rise faster than they were being consumed. At the end of January we stopped dosing either of the duo but, since then, my calcium has risen to 540 and magnesium to 1665 (from 450 and 1335 on 29/01). My kh has fallen however, from 10.1 to 7.7.

This has thrown up a lot of confusion for me! Is it possible that something is leeching the calcium and magnesium back in to the tank?? I'm not running any other medias, just a Clarisea and skimmer in the sump with the bio blocks and live rock.

I'd really appreciate any help/advice!

Many thanks,

Gary

 

[P-Dub]

Hi Gary.
Chances are the salt you are using may have elevated levels. Additionally, Alkalinity and Calcium levels are somewhat interdependent. Up your Alk levels to be balanced with your calcium levels and then try Kalkwasser instead to maintain a balanced dosing schedule.

 

[barrybigbum]

Hi Gary.
Chances are the salt you are using may have elevated levels. Additionally, Alkalinity and Calcium levels are somewhat interdependent. Up your Alk levels to be balanced with your calcium levels and then try Kalkwasser instead to maintain a balanced dosing schedule.

Hi mate,

Thank you for the reply.

As mentioned in the original post, I am using Natural Sea Water so no synthetic salt involved.

The first test results were OK (04/01 - Cal = 415, Mag = 1350, Alk = 7.9).
On 05/01 - Cal = 440, Mag = 1395 and Alk = 7.7 and on 06/01 - Cal = 420, Mag = 1350 but Alk stayed at 7.7.
On 10/01 - Cal = 405, Mag = 1380 and Alk = 8.4 but on 14/01 there was a bit of an Alk jump (Cal = 440, Mag = 1320 and Alk = 9) so we agreed to reduce both parts of the duo slightly. Alk continued to rise (reached 10.6 on 22/01) so we dropped that back more until we eventually stopped it on 22/01 (it hasn't been dosed since).
On 29/01 the results were Cal = 450, Mag = 1335 and Alk = 10 1 so we stopped dosing the Calcium as well and then on 04/02 results were Cal = 445, Mag = 1350 and Alk = 8.6.

On 08/02 Cal = 485, Mag = 1470 and Alk remained at 8.55. At this point I was told that my Cal and Mag test kits must be incorrect (Nyos) so I was told to order Salifert. I did this and then tested when they arrived (13/01) which gave me the results listed in the original post.

As you can see, it's happened in the last fortnight and surely can't be linked to the Natural Sea Water that was put in in December?

I'm baffled to be honest.....!

Gary

 

[otimer]

Hi,
Don't you measure pH periodically?
I believe that extreamly low pH increases alk and Ca. And reduction/consumpion of nitrates in the tank will increase them as well.
Son

 

[barrybigbum]

Hi,
Don't you measure pH periodically?
I believe that extreamly low pH increases alk and Ca. And reduction/consumpion of nitrates in the tank will increase them as well.
Son

Ph is monitored permanently via my aquatronica which has been recently calibrated. It stays consistently around 8.02. My nitrates are currently 4 (they were much lower but have increased)

 

[P-Dub]

Hmmm. Gotta say I'm stumped too. Have you thought about testing your seawater just for the heck of it?

 

[barrybigbum]

Hmmm. Gotta say I'm stumped too. Have you thought about testing your seawater just for the heck of it?

I thought my first set of results would cover that. What is stumping me the most is the fact that it was OK but has changed over the last fortnight.....

 

[Randy Holmes-Farley]

I thought my first set of results would cover that. What is stumping me the most is the fact that it was OK but has changed over the last fortnight.....

It is almost certainly either a salinity rise, or just random test variation/error. There's no way for them to rapidly rise on their own.

 

[barrybigbum]

It is almost certainly either a salinity rise, or just random test variation/error. There's no way for them to rapidly rise on their own.

Thanks Randy!

I can only think it would be a test error but I've used two different kits which are both well within their BBE date.

I'm really baffled by it but don't know what else to try/do.....?

 

[P-Dub]

I thought my first set of results would cover that. What is stumping me the most is the fact that it was OK but has changed over the last fortnight.....

Truly baffling.

 

[Neuratox]

Any progress on this? I've been seeing consumption of Alk in my reef tank (used Marcos dry rock and mortar), but no change, perhaps even a slow increase in my calcium over the period of about 1.5 months. I haven't done a water change in that period of time either (was battling dinos). I'd love to know if you found out what was causing your issue.

 

[Randy Holmes-Farley]

Any progress on this? I've been seeing consumption of Alk in my reef tank (used Marcos dry rock and mortar), but no change, perhaps even a slow increase in my calcium over the period of about 1.5 months. I haven't done a water change in that period of time either (was battling dinos). I'd love to know if you found out what was causing your issue.

Alk is depleted by rising nitrate and calcium can be added by very slow dissolution of rock and sand (alk too, but the depletion might over power it).

There are not a lot of undiscovered explanations for chemical changes in a reef tank.

 

[Neuratox]

Alk is depleted by rising nitrate and calcium can be added by very slow dissolution of rock and sand (alk too, but the depletion might over power it).

There are not a lot of undiscovered explanations for chemical changes in a reef tank.

Hey Randy! Thanks! I spent some of last night reading up on some of your publications. VERY helpful! Thanks for all of your valuable contributions to the community and improving the knowledge and success rate of so many!