Seeking Chemistry understanding

[Rolliad]

I'm sure this is somewhere else, but I'm just recovering from Norovirus, so please bear with me.

My understanding of Alk and Ca is that they have a bit of an inverse relationship - the higher the Alk, the lower the Ca...etc.

The last few weeks, my Alk has creeped up and up and up, for no reason that I can identify. The only thing I've dosed the last 3 weeks is PhosBan - L, which says that it would actually decrease Alk, not increase it. However, my Alk has gone from 8.9 to 11.2 over the course of the last 3 weeks. My normal water change of 10% reduces it for a bit and then it creeps back up again over the course of the week.

Becoming a bit concerned that I have a Ca problem, I've tested my Ca for the last week...and my Ca is also slowly creeping up. This makes no sense to me based on what I know of how this works.

Here are my tank parameters as of this morning:

Temp: 79.1
Salinity: 1.025
pH: 8.35
Nitrates: 35.4
Phosphates: 0.15
Alk: 10.8
Ca: 480
Mag: 1440

I have a bunch of SPS and a few LPS and a couple of leathers. Everything looks fine.

I'm just trying to capture understanding on if I have a problem in the making or no?

 

[Pod_01]

Not sure about the inverse relationship of Alk/ Calcium.

If Alk is going up and Calc is going up I would reduce any 2/3 part/ AFR etc… dosing.

Next I would check salinity to make sure it has not crept up…
Alk and Calcium do not tend to increase unless they are added or salinity changed.

Good luck,

 

[Randy Holmes-Farley Verified Community Expert]

Alk and calcium are not really inverse. That's an oversimplification to the point of inaccuracy. Both can be high or both low.

Are you dosing anything?

 

[Rolliad]

I've triple checked my salinity and it's 1.025 on all testers.

I'm not dosing anything except for PhosBan - L to bring my phosphates down.

 

[Garf]

my Alk has creeped up and up

You sure you aren't reading the test upside down, or backwards?

 

[Randy Holmes-Farley Verified Community Expert]

How do you replace evaporated water?

 

[Rolliad]

You sure you aren't reading the test upside down, or backwards?

Haha! Yes I am. :)

 

[Rolliad]

How do you replace evaporated water?

RODI with ATO pump controlled by Hydros controller.

I used to dose Kalk, but stopped about a month ago to make sure I get everything dialed in prior to further utilization.