New tank with 8.6 pH?

[Crow]

I just setup my new 93g cube, running the following: caibbsea Fiji pink sand, BRS pukani dry rock, instant ocean salt.

I calibrated my Neptune apex using the supplied regent last night and it's been reading 8.6 all night.

No lights are running as the rock is still curing and has been for three weeks, I've done two 100% water changes, with the last one being about four days ago.

I have never had pH this high ever in any tank I've had over the past twenty years, hence the reason of my post as I am at a loss.

 

[Crow]

Some forgotten info...
I am using RO/DI water, and according to the same probe that is in the tank my RO/DI has a pH of 7.6.

 

[Randy Holmes-Farley]

What is the alkalinity?

I suspect the pH may be an error, but a real pH 8.6 is not a problem and will decline once the biology gets going.

 

[Crow]

I'll check the alkalinity and get back to you, thanks.

 

[Randy Holmes-Farley]

There are no artificial rocks or cement things in the tank, are there? That can raise pH a lot.

 

[Crow]

3.5 Meq/L - 9.8 dKH
Nope, only thing in tank is dry rock, sand. Only things running is filter sock, return pump and skimmer.

 

[Keithcorals]

It likely will go down in a day or two. If it's still that high after a few days I'd start testing for problems with the probe

 

[Crow]

More info just incase.
Only thing added to the water other then salt was a bottle of bio-spira.

 

[Randy Holmes-Farley]

pH doesn't get excessively high without adding high pH additives, so I would't worry at the moment.

 

[Crow]

Thanks Randy, like I said, I've never ran into this issue before.

 

[Crow]

http://www.reeftronics.net/cn/crow/apex-status

 

[Randy Holmes-Farley]

Looking at the graph, I suspect it is slightly miscalibrated.

What fluids did you use?

 

[Crow]

Randy, I used the 7.0 and 10.0 fluids that came with the apex gold. I couldn't tell you the exact name as I threw them out after.

I did put the probe back into each packet after calibrated to see if it read the 7.0 and 10.0, but I guess if the regent was bad that wouldn't matter.

 

[Randy Holmes-Farley]

I don't know if it is the issue or not, but pH 10 calibration fluids can drop in pH over time, making the measured pH look higher than it really is.

 

[Crow]

Update: Randy, just wanted to update this with what I've done to fix the issue. I went to my LFS and bought new packets of testing regents. And did a recalibration, and now it looks correct. It went from a 8.6 to a 7.5 after recalibration.

Thanks for your info.

 

[Randy Holmes-Farley]

OK, thanks for the update.