How measure PH?
 

I have been using the Elos kit to test PH and the test comes out red which is closest to the light purple on their colour chart - PH 8.3

Since the red is quite different than the light purple I thought I'd try a different brand of kit and make sure I am interpreting the test correctly. I bought a Nutrafin kit and it says my PH is 7.5:question:

I am amazed at the huge range from one brand to another. :neutral:

My alkalinity has been dropping steadily so I was looking at buffering it. Some products lower PH while others raise it. Hard to tell what to use when I don’t know what the PH is.

How do you guys measure PH accurately? Should I get a probe?

Not sure what's going on with your test kits. Is the Elos brand new? Maybe it's a faulty batch. I'd email them.

Personally, I don't use any buffers that directly alter the pH. Too dangerous in my opinion. I use SeaChem Reef Buffer it only adjusts the alkalinity. Since pH and alkalinity are related, the buffer will alter the pH indirectly, unlike the ones that "buffer to pH 8.3".

I use Salifert for testing pH, or a Pinpoint pH monitor. All test kits are notoriously inaccurate for pH. Although they are close enough for what we need them to do.

I don't normally have a problem seeing colours but tried different pH testkits and found all just a pain.

Probably not a big deal if not dosing as things should stabilize but since I'm running a reactor ended up getting a probe.

I was looking at http://home.comcast.net/~jdieck1/chemcalc.html and according to that site SeaChem Reef Buffer make PH "Substantially Higher!"

You could always see if a fellow Reefer in your area with a ph meter can stop by and do a quick test... just make sure it has been calibrated... just a thought...

Buy a pH meter. It'll pay for itself with use anyway. Get some calibration solution when you order it and calibrated every couple months. It's just easier, quicker and probably more accurate.

You know...I ran my first tank for twelve years and never really measured the pH. I don't think one should attempt to change the pH anyway. Especially NOT if you are not 100% dead accurate with pH measuring. Besides, to get a truly accurate reading of what your tank is doing you would need to measure ever hour for a 24hr period because there is a daily cycle.

So..go ahead and measure pH. It's fun. But don't try to change it!

Control your Alkalinity (and Ca), and the let the pH do what it does.

(Hypocritical advice as I am currently attempting to control my daily pH swing using my Kalk reactor...but I think that is different...)

^^^^ I second what untamed said.

One exception, you DO want to measure pH of a reactor's effluent, and forget trying to use test kits for that. You need to know the difference between 6.6 and 6.7 and 6.8 and you really need a meter for that sort of thing. 6 years ago I tried dialing in a reactor using pH test kits. That lasted about 3 weeks. Bought a meter and never looked back.

I'm not looking at controlling PH. I'm trying to determine which product to use to raise alkalinity. Some, such as baking soda, lower PH while many comercial products raise it. I was trying to determine whether a product that raised PH or lowered it would be beter to use.

Holmes-Farley did an excellent article on the affects that alkalinity supplements have on pH. This should answer your question.

Here's the article:
http://www.advancedaquarist.com/issues/may2002/chem.htm