Need Ph help

[manoverboard]

Ive been trying to dial in my RKE ph probe ,bought it used and was using the old ph probe .At about noon with the lights on i calibrated it using the 10 and 7 calibration fluids 2 times just to make sure.My ph was reading 8.25 .The next morning my ph was 7.4 :eek1:.I tested the water with a salfert ph test kit that was in date the ph tested at about 8.0. I checked the calibration again on my probe it was fine.????
So, i bought a new sybon lab grade ph probe.This morning i did a double calibration with ro dips between and my ph is 7.6.Again selfert test showed 8.0.
I run kalk in my topoff via perastaltic pump.(im in the process of trying to dose only at night via topoff gotta get a light senser.
54 corner 5 months old
flow= Danner 9.5 return with a sqiud,1 vortech mp10 and 1 tunze 6025,
12 hour light cycle 250w 14k phoenix
algae scrubber ran in reverse cycle of tank lighting a little overlap though
euroreef skimmer 24/7

nitrate 1 ppm
phosphate .03 ppm
alk 9.5 dkh
calcium 420ppm
mag 1100ppm
tank temp 78-81

1 yellow tang 3 in
2 clowns small
2 damsels
1pencel urchen
alot of hermits 2 emeralds
mixed reef
alot of hair algea but im fighting it keeplig it in check
corals doing ok but growth of lps and sps slow

 

[Percula9]

Sometimes pH meters can experience electrical interference. Measure a cup of water away from the tank. I doubt your pH is that low.

 

[Cantgrowdidly]

Make sure the probe isn't near any pumps or ballasts.

 

[bertoni]

I agree that electrical interference can be an issue. There might be some issue with water circulation, I suppose, or the tank might have aeration problems. A surface film of some sort can cause a large pH drop, for example. I wouldn't worry much at this point, but I'd start checking that the pH measurement was okay.

 

[manoverboard]

ph

ph

The cup of water sample worked shows my ph at 8.12 still wish it was a little higher.As for film on the top of the water i have a top overflow on the tank and 20x the tank volume of water flow.(no sheen)
Guess now i have to track down the potential stray voltage .Can you test it with a meter?id bet it is my top off float Ive been shocked by it before.
Thanks for the help guys

 

[disc1]

The cup of water sample worked shows my ph at 8.12 still wish it was a little higher.

Why? Why mess with perfection?

 

[bertoni]

If something in the tank is causing shocks, I'd pitch it. The shocks could turn into something worse.

For electrical interference, you could try moving the power line away from any other power line or other wiring, and perhaps measuring the pH in a cup of water, rather than the tank itself. Any difference in the pH level would be suspect.