Low calcium, normal Alk in Ca reactor

[Shotscane]

So I have a Geo 818 calcium reactor. My alk is 9 magnesium is 1400 but my calcium levels only 340. This seems low to me. If I turn the effluent up anymore my alk climbs and my euphylias start to close up. Any explanation of how this is possible and what solutions to fix the problem? Thanks in advance.

 

[Diesel]

Turn effluent down and you create a more internal circulation which will help to have you CAL coming up a bit.
What is your effluent rate as we speak (ML per minute)?
What kind of media in your rector you use?
What is your bubble count and what kind of regulator do you use?

 

[Randy Holmes-Farley]

The calcium MUST be corrected manually with calcium chloride, not with the reactor. To boost calcium by 80 ppm using a CaCO3/CO2 reactor will shoot the alk through the roof, to more than 20 dKH.

 

[Shotscane]

I'm currently using the two little fishies media with their remag. I filled the reactor to the top (per geo it said is 28pds I believe) and the 2.2 pds of remag. I don't know if the remag sold by them is dolomite or not and that's what could be causing problems? I'm using a carbon doser connected to the Apex keeping ph within the rx between 6.5 and 6.7. I'm dripping approximately 2.5ml/min. I have been making hand corrections with CaCl but this is the second time I've had to do this. I thought the point of the rx is to dose both alk and Ca in equal portions? Thank you both tremendously for your advice and help!!

 

[Shotscane]

Also my bubble rate is set at 9 seconds per bubble, but the apex often shuts the reactor off due to the ph within falling below my set parameters.

 

[Randy Holmes-Farley]

Just remag? Or just the 10% recommended? Using pure Remag is not appropriate. It will boost alkalinity and magnesium too much relative to calcium.

What salt mix are you using?

 

[Shotscane]

I'm using just 10% of the remag. And I use the plain instant ocean.

 

[Randy Holmes-Farley]

The IO is likely the issue (or part of it). It has more alkalinity than calcium (relative to NSW), and if you let the alk in it decline to 9 dKH, calcium will decline below NSW values. Try boosting new IO salt water to 440 to 460 ppm calcium before using it. No need to measure it if you don't want. Just add calcium chloride to give a boost of about 40 ppm.

 

[Diesel]

I'm currently using the two little fishies media with their remag. I filled the reactor to the top (per geo it said is 28pds I believe) and the 2.2 pds of remag. I don't know if the remag sold by them is dolomite or not and that's what could be causing problems? I'm using a carbon doser connected to the Apex keeping ph within the rx between 6.5 and 6.7. I'm dripping approximately 2.5ml/min. I have been making hand corrections with CaCl but this is the second time I've had to do this. I thought the point of the rx is to dose both alk and Ca in equal portions? Thank you both tremendously for your advice and help!!

You might want to test your effluent on ALK, CAL and MAG
Dosing 2.5 ml p/m isn't enough
My CaRx is set to 60ml p/m and when I had full SPS 120ml p/m
Of course those # were based on the ammount of consumption of your tank.

I used the reborn as well in two canisters and my main had a whole bag of Remag.
One bubble every two seconds and set on the Co2 low pressure of 6 as that will depends how big your bubbles getting.
My ALK was tested daily at 7.5, CAL weekly test 390 and MAG on a weekly test as well at 1320 give and take.

 

[Shotscane]

The IO is likely the issue (or part of it). It has more alkalinity than calcium (relative to NSW), and if you let the alk in it decline to 9 dKH, calcium will decline below NSW values. Try boosting new IO salt water to 440 to 460 ppm calcium before using it. No need to measure it if you don't want. Just add calcium chloride to give a boost of about 40 ppm.

Thank you again for your advice! So in theory once I raise my calcium level within the tank and if I keep my Alk at 9 my current calcium levels should maintain? If it does not, are there any other culprits that could cause my Ca to drop while my Alk remains stable?

 

[Randy Holmes-Farley]

Thank you again for your advice! So in theory once I raise my calcium level within the tank and if I keep my Alk at 9 my current calcium levels should maintain? If it does not, are there any other culprits that could cause my Ca to drop while my Alk remains stable?

Yes. Aside from water changes, it should do a good job of maintaining calcium. Minor tweaking may still be needed since you are guessing at the ratio of calcium to magnesium that is both added and consumed.

The other effects are minor:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

[SUS]

I know this is an old thread, but I’m having similar issues... been running a carx for about a year. Alk is stable around 9 but cal is always low. It Was at 360 last week, brought it up via cacl to 410, and now it’s back down to 360 a week later. I use reef crystals which I just tested at 470. Is it normal to have to continue dosing ca while using the carx? I use the arm coarse/extra coarse media.
also, my mag is 1320-1330
@Randy Holmes-Farley