Cal @ 850ppm Ph @ 6.39 help please...

[The_Crabman]

So here is the problem, Friday night I do a calcium test ant the Hanna checker reads 265. This is quite low so I adjust my dosing pump to increase the dosage and nothing comes out the end of the hose.
I check things and it appears that a little build-up of crystals on the end of the hose has prevented the solution from reaching the tank.
I clean and set things up again and go about my evening.

Saturday I come into the basement, at around 7:30am, where my aquarium is and notice that my dosing pump for my calcium solution is running along with my dosing pump for my Mag.
I find this strange as I set my events so that there is only one pump running at a time.
I then look down at the jugs of solutions to find that the one with the calcium solution has been almost sucked inside out. It had been half full the night before approx 1 gallon of solution had been pumped into my aquarium.
The jug with the Mag solution was fine and only down a little from the night before.

I have a 150gal system and do a 10% water change approx every 10 days.
I had the water ready to go so I do a water change.
I then check parameters,

Calcium reads 564 on the Hanna checker. I think this is great as I thought things would be higher.

My Alk is at 9.01 (Hanna checker), I think its high but plan to do another water change as soon as I can make another batch of water.

I check my Mag and find it at 1800ppm (sailfert) This is higher than I keep it but I've used high Mag to cure and outbreak of bryopsis before and I also figure that I will be doing another water change so this will lower it too.

Last, I check my Ph. Its low at 6.35 (D/A probe). I figure this is a mistake and set out to recalibrate my probe. The reading I get is still in the low 6's.

I check the reaction in my tank, all fish seem to be well, a few snails are upside-down, two blood shrimp and one coral banded shrimp are kinda lethargic, they are out in the open sitting on the sand bed and not moving much. My sand sifting star is sitting on the substrate, arched with just his tips touching the substrate. I have one acro that has lost about 30% of flesh, two of my styliophoras are retracted along with a tri-color birdsnest.

Sunday morning around 7am I do a 15% water change and test the water again...
Cal = 498 I think that things are working out
ALK =7.89 this is good as I keep my alk at around 7.70
Ph = 6.70

I check for reaction in the tank, fish are okay, one of the blood shrimp molted over night, coral banded shrimp lethargic along with one of my blood shrimp. Polyps still retracets on the stylo's and the birds nest. All flesh off of the acro and some off of another..

I now think that I have a Ph problem and that the calcium is okay.
I do an aeration test to see if its a Co2 problem, I take a cup of water out of the tank and drop the probe into it only to find that it reads about 7.6 which I think is cool but when I drop it back in the tank it goes down to 6.5 again. I do this 5 or 6 more times with the same results which confuses me.
I open a window to change the air in the house to see if that helps and check

Today, Monday one of my blood shrimps is dead along with one of my acros. Two other acros have lost 40% of their flesh. I'm getting ready to do another water change but decide to test parameters again,

Ph is still 6.4 so I re-calibrate my probe once again still 6.4 ao I use a Red-Sea Ph test kit that I have around. I can even get it to register a color that is on the chart so I assume that my probe is correct.

Alk is still at 7.89 so that is steady.

Calicum reads 600 on the Hanna checker I find this odd so proceed to verify with an Elos test to my suprise I get a reading of 850.
I check it again with the Hanna and get a reading of 580, I check it again with the Elos kit and get 850 again.
I research the Hanna only to find out that it will only read upto 600ppm.

So there you go, My Cal is extremely high at 850ppm.
My Ph is extremely low at 6.39.
The Calcium is not percipitating, I assume this is because my Mag is high.

I'm going to keep doing water changes to correct the calcium problem but I wonder what I should be doing about the Ph problem.

Help?

[Randy Holmes-Farley]

I do not believe the pH is even close to accurate. The rock will be dissolving like in a CaCO3/CO2 reactor and the alk would consequently be far higher.

Try measuring pH in a cup away from the tank, in case there is electrical interference.

[The_Crabman]

Thanks for the quick response Randy...

My Ph reading was 6.65
I put the probe 8ft from my tank in a cup of tank water and the Ph is 7.75
I threw the probe back into the tank and it reads 6.69I put another cup of water, stood it on my frag rack inside the tank, threw in the probe and it reads 7.75
Probe in the sump reads 6.7 probe in cup in sump reads 7.74

I guess that there is possibly some stray voltage in my set-up?
Your thoughts...

[Randy Holmes-Farley]

Could be through the air electrical interference from things like lighting ballasts. Maybe turn off the lights (or wait till evening) and see if it changes anything.

It may also be a grounding loop. Some hobby controllers have such an issue. Here's a discussion of that problem:

http://www.all-about-ph.com/ground-loop-problems.html