Alkalinity issue

[zanclus]

Hi i seem to be chasing a dead horse here. I have an 80 gallon with a 40 gallon sump I estamite 100 total gallons. I am Using zeovit and all seems yo be going hood except my Alk seems to be low. I understand that in a zeovit system Alk should be between 6.5-7.5
. My issue is my alk keep dropping to 5.4 . I have been checking at 8pm every wvenkng and its 5.4. Every time I manually raise the Alk to 7 , it falls back down within 8 hrs.
My parameters are as follows...
SG 35ppt Both refractometer and digital
Cal 420 Salifert
Alk 5.4. Hanna Colormeter
Phos 0 Hanna Colormeter
No3 .25 Salifert.
Mag. 1340 Salifert
I dose 110ml if soda ash (BRR) every night via a Apex DOS. Any ideas????

 

[CNDReef]

How much calcium are you dosing daily and is it also the Brs calcium?
Just sounds like you’re consuming more alk than your dosing. Might try adding a additional 1/4 dose of alk during the day then test again at your normal time to see if it dropped less. If it dropped less keep adding a little more every day to the total dose until you reach your desired value.

 

[zanclus]

I have been dosing 72ml and yes BRS

 

[zanclus]

I tested tank at same time ,12 pm, calcium 400 Dkh 6.6 , Mag 1340. I increased the dosing to 120ml each (calcium and Alk) yeasterday to see what happends... will continue and see where I am tomorrow.