Calcium and Alkalinity balance

alvinhsu

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Hi,

So I have been trying to figure out how get my calcium and alkalinity to stabilize. I have a kalk stirrer (6.4 liters a day) , running in conjunction with a calcium reactor, the effluent goes into a chaeto reactor. I have been able to dial in my alkalinity go between 9.0 in the morning - 8.6 at night. However my calcium goes down over time. It was around 440 at the beginning of the month, and has dropped down to ~400 as of today (checked with Hanna and Red Sea). I always assumed that calcium and alkalinity are consumed at a fixed ratio, so if I lose 0.4 alk during the day, I lose a proportional amount of calcium, and over night when the alkalinity get replenished by the reactor it goes back up to 9.0, and the same proportional amount of calcium is added back. So I am not sure what the source of this calcium "decay" is.

some details on my tank

Gear

- 180 gallon
- avast marine K2 kalk stirrer
- destaco C2 calcium reactor
- pax bellum N18 chaeto reactor

Water parameters
- alk 9.0
- mag 1290
- PH 7.8 - 8.1
- temp 77
- NO3 0.16
- PO4 0.07

dosing
- brightwell neomarine salt
- brightwell chaetogro
- seachem reef plus
- brightwell neonitro

Live stock

- all stony corals, mix of acros, montis, gonis, favia/favites, anacros, various euphyllia , around 40 frags in total.
- fish around 20 fish in total
 

Randy Holmes-Farley

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The nitrate dosing is likely what’s doing it. Consumption of that nitrate boosts alk, so the alk is partly maintained that way, leaving calcium underdosed.

I’d just add calcium chloride to maintain it.
 
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arking_mark

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I would suspect the unbalance is coming from the Neonitro. Adding NO3 to the tank that then gets consumed by denitrification produces Alk. So in effect, you are adding unbalanced Alk through the denitrification.
 
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alvinhsu

alvinhsu

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The nitrate dosing is likely what’s doing it. Consumption of that nitrate boosts alk, so the alk is partly maintained that way, leaving calcium underdosed.

I’d just add calcium chloride to maintain it.
thanks! I didn't even think about the nitrate dosing as being a potential source of calcium decay. Dripping calcium chloride now to bring it up.
 
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Randy Holmes-Farley

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thanks! I didn't even think about the nitrate dosing as being a potential source of calcium decay. Dripping calcium chloride now to bring it up.

I’m not sure Brightwell understands that Neonitro adds alk, but it would be appropriate to add it to the description.
 
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