Alkalinity Rising - Beyond Perplexed!

[Chipper1978]

My Waterbox 130.4 is 8 months old. Marco Rock, refugium with chaeto (running light overnight), BRS GFO in reactor, protein skimmer, floss, and bag of BRS carbon. Parameters (see below) have all been very stable with minimal coralline taking hold. Weekly 10-15% water changes with Marin Pro salt, weekly Acropower (after water changes), and Reef-Roids 2-3 times per week. Feed my mixed reef with fish a variety of Reef Frenzy, PE Mysis, spirulina, Hikari marine pellets, Hikari Seaweed Extreme pellets, and nori. Also add Algae Barn phyto daily.

calcium-448, mag-1360-1400, NO3-11.7, PO4-0.03-0.06, salinity-1.025, temp-77.9

dKH sits around 8.0, but goes up to 8.4 after about 24 hours after water changes. By the end of the week it’s back down to 8.0. Considering my salt mixes at 7.5 (I’ve tested it), why would my dKH not go down? Something leaching from my rock or the sand? Could the Acropower or Algae Barn phyto be increasing it? I am very confused!

 

[Randy Holmes-Farley]

At 15% of the water changed, to get a 0.4 dKH rise in the alk, the new salt water would need to be 10.7 dKH. Assuming that is not the case, I expect the 0,.4 dKH rise is not going to happen over and over and is just a measurement issue.

While there are some things that will steadily boost alkalinity, they do not stop and start like that.

 

[Chipper1978]

At 15% of the water changed, to get a 0.4 dKH rise in the alk, the new salt water would need to be 10.7 dKH. Assuming that is not the case, I expect the 0,.4 dKH rise is not going to happen over and over and is just a measurement issue.

While there are some things that will steadily boost alkalinity, they do not stop and start like that.

Thank you, Randy. I use a Hanna tester to measure my alkalinity on a daily basis. It has always provided me with very consistent readings. Do those things ever need to be recalibrated?

 

[Chipper1978]

Also, I have tested the saltwater for the water change and it is 7.5. Has to be something I add (Acropower, phyto, etc.) or leaching from somewhere.

 

[Randy Holmes-Farley]

Also, I have tested the saltwater for the water change and it is 7.5. Has to be something I add (Acropower, phyto, etc.) or leaching from somewhere.

I still think just test error and I'd just keep watching. The rise is not much to worry about if real.

If it was one of those additives, why doesn't it repeat when you dose them again during the week? If you only dose them once a week, separate them from the water change to distinguish the effects.