pH meters are giving me consistently low readings for saltwater.

[Parad1s3lost]

So here's my story:

I bought a Hanna pH meter called the checker, it was a cheapie, cost me like 40 bucks came with what is probably a cheap electrode but i just wanted to be able to check pH of my tank and water changes on the fly.

What follows is a story of my grief lol

Anyway, so i calibrated the pH meter with pH7 and pH10 buffer, two sets, one that came with the meter and then some 7 and 10 buffer i brought home from work (i work as a chemist).

It calibrated just fine for the solutions, however when i went to test the pH of my saltwater in my display tank, it was giving me readings much lower than what i was getting in my dropper pH test.

I thought, oh damn i just wasted 40 bucks on this piece of junk , anyway so a couple days later i decided to take a sample of my tank water to work and check it with one of the pH meters in my lab (which costs ALOT more than 40 dollars ), the meter was calibrated at 7 as well, and when i checked the pH of my tank water with this 500 dollar pH meter, the SAME!

the pH both meters were giving me was in the range of 7.7-7.9 when the dropper test clearly was giving me readings of 8.2.-8.3 every time.

So i guess what my question's are..

1. What am i doing wrong?

2. Does the measurement of the pH of seawater require a specialized type of probe? I wouldn't think so..

Anyway thanks in advance for your responses.

[golfish]

What dropper test kit are you using. I'm not a chemist but I do work in a lab, I tend to agree with what I get from the lab.

Are you running a Calcium reactor? What are your Alk and Ca levels?

A lot of the dropper kits tend to give you readings you "want" to see...

[Parad1s3lost]

Kit - Red Sea 7.4-8.6

One thing really bothers me though, I picked up some boxed natural sea water (5 gallons) today @ the LFS and on the side of the box it said the pH is approximately 8.3 and the pH meter i have read 7.98

My tank is a FOWLR. I just recently started maintaining the Calcium to try and get some coralline algae to pop up, but it is only though the addition of Seachem Reef Complete. It us usually in the neighborhood of 330 mg/L

The alkalinity has been pretty stable it has been around 2.8/3.0 meq/L since i've set up the tank.

[golfish]

throw that same boxed water in a bucket and run an air stone for a few minutes and see what the ph is....

Red Sea test kits are "ok" at best..I feel your meters are right on.

Are you having problems that you feel are caused by low ph?

[Parad1s3lost]

Other than an ich outbreak that my fish seem to be fending off rather well on their own, there isn't any problems. I just wanted to start bringing my pH up to around 8.3 over the next week or so to try and see if it will stimulate more coralline algae growth.