Test kits

[missavgp]

I wanted to ask what water testing kits people find the most reliable. I am having an issue where the API pH test is reading 7.6 and the Hagen Nutrafin pH test is reading 7.0. I am actually working on bringing the pH in this tank down (betta macrostoma prefer soft low pH water) but I need an accurate reading to work with. What have other people found?

[fischkopp]

It's always difficult to judge the colors on these chemical test kits. This really affects accuracy and adds a subjective error to the results. But they are ok for a general trend +/-0.5, and produce pretty much all the same results.

For reliable results its better to use an electronic probe. Spectrographic measurements should be pretty accurate too, but I can't comment on these since I have never used them.

[Philnashbass]

I've always found these type of kits to be reliable. Variables like expiration date, settled product/unshaken bottles, hand oils, cross contamination of water sample with tap water etc. should be considered (I'm sure you are already aware of this).
When I'm in doubt, I dump, rinse with tap water, rise with tank water and retest.

[mm]

I find this type of digital ph meter cheap and reliable over a wide range of ph values (once calibrated):

http://www.amazon.ca/HDE-Digital-Aquarium-Hydroponic-Monitor/dp/B00IEJOI9S/ref=sr_1_2?ie=UTF8&qid=1428782055&sr=8-2&keywords=ph+meter

They are easy to calibrate too. I use them to monitor the pH in my blackwater tanks with pH around 5-6, my "Ottawa water " tanks with a pH around neutral, and my Tanganyikan tanks at around 8.0.  No liquid test that I know covers this wide range with this precision. This is not a high-end electronic probe but it does the job really well and it is dirt cheap.

The shipping takes a few weeks but I can lend you one for a while if you need.