Huge kH consumption and cloudy water

[MarcinPl]

Hallo. Long time lurker, first time help-seeker here.
Last week I was on vacation. 5 days ago I noticed that the pump in my sump died - there was no circulation between sump and display tank for 2-3 days.
I run to the car and come home. By my arrival, 90% of fish were dead, but corals intact.
NO3 went through the roof. PO4 was somehow high but ok. I took out all the dead ones and did 10% water change. I also added new carbon and went back for vacation.
The water, was crystal clear. I also added a lot of bacteria
I come back 3 days
(Aha, I dose ATI Essentials+)
Everything is ok, no corals or further fish were lost, however the water is incredibly cloudy and ATI1 (the one with ALK) consumption grew from 78 to 200 ml per day.
Did another 5% water change, and added MG but no results.
ATI1 turns very cloudy upon dosing and ALK is falling very fast (I need to dose 3x as much as normal to keep it at certain level)
I suspected low MG and added some, but without impac\
Water parameters:
ALK: 8,3-9,2 - it is very unstable, falling very fast
NO3: 4
PO4: 0,02
CA: 445
MG: 1353 (However it was around the same value before, adding MG doesnt seem to have raised it much)
Salinity: 1,026
PH: 8,1 - 8,4 (Fluctuates day/night, I use CO2 scrubber)

I also run carbon and GFO
Any ideas how to calm my alkalinity ?

 

[Randy Holmes-Farley Verified Community Expert]

If any of the cloudiness is precipitation calcium carbonate, you need to let that settle out and get coated with stuff to prevent more precipitation before adding more additives. They just act as seed crystals to remove alk and calcium as fast as you add it.

Thst said, rising nitrate also depletes alk and that scenario seems likely.

 

[BTAlover]

If any of the cloudiness is precipitation calcium carbonate, you need to let that settle out and get coated with stuff to prevent more precipitation before adding more additives. They just act as seed crystals to remove alk and calcium as fast as you add it.

Thst said, rising nitrate also depletes alk and that scenario seems likely.

This makes perfect sense. Could you elaborate on "and get coated with stuff?" It's impossible to remove the precipitate (other than what may have congealed on the bottom of the tank) since the precipitate is in the water column, too small to be filtered by socks.

 

[MarcinPl]

It helped once I stopped dosing ATI for 24hrs. However the cloudiness tends to come back.. I consider switching to another bailing liquids.