Alkalinity Mysteriously Rising

[FoolintheRain]

I have a 32 Biocube that is 6 months old and over the past month the alkalinity has been creeping up unexplainably from 8dkh to 10.5 dkh when I measured today. I have done weekly 5 gallon water changes with RODI water and HW Marine salt since the tank was setup and consistently measure the new water at 8dkh. Two weeks ago it was at 9.3 and I did 3x 30% water changes two days apart and got it down to 8.4 and figured it would slowly drop back down to 8.0 over time.

Parameters today:

Sg: 1.026
Temp: 77-78
pH: 8
NO3: 3 (Red Sea and Nyos)
PO4: .02 (Red Sea and Hanna)
Ca: 440-450 (Red Sea)
Mg: 1350 (Salifert)
dKH: 10.5 (Hanna and Red Sea)

Fish:
2 clowns
2 firefish
1 YWG/shrimp pair
1 BCS

Coral:
Xenia
GSP
Cloves
Zoas

I do not dose anything to the tank and filtration is chemi pure elite and purigen in the AIO basket with a small ball of chaeto running 12 hours at night. Tank was started with reefcleaners dry rock which I had cooking for 3 months before the tank was setup almost 6 months ago. Has about 2 inches of Tropic Eden Miniflakes and Mesoflakes.

Should I try pulling the purigen or the chemipure elite one at a time and see what happens?

 

[JCOLE]

How often do you measure Alk? Do you test daily?

 

[FoolintheRain]

Usually once a week but two weeks ago started testing every day when I was doing water changes to bring it down.

 

[JCOLE]

If you aren't running any medication then I would remove the purigen and chemipure. Also, I would stop water changes for a little while and let your system stabilize. Test ALK daily and you should see it come down. If you corals aren't consuming ALK fast then water changes of the same dKh will keep it in check. If not, then I would start dosing to keep your levels stable.

 

[FoolintheRain]

Do purigen or chemi pure cause alkalinity to rise like this? I am not running medication but they are the main nutrient control so reluctant to just pull them out. And there are only soft corals so don't anticipate needing to dose.