New tank with 8.6 pH?

Crow · Nov 20, 2014

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 · Nov 20, 2014

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 · Nov 20, 2014

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 · Nov 20, 2014

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

Randy Holmes-Farley · Nov 20, 2014

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

Crow · Nov 20, 2014

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 · Nov 20, 2014

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 · Nov 20, 2014

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

Randy Holmes-Farley · Nov 20, 2014

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

Crow · Nov 20, 2014

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

Crow · Nov 20, 2014

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

Randy Holmes-Farley · Nov 21, 2014

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

What fluids did you use?

Crow · Nov 21, 2014

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 · Nov 21, 2014

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 · Dec 7, 2014

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.