Electronic vs. solution-based ph testers

[markwill]

I have a "Freshwater Test Kit" (can't remember the make but I've seen them in a bunch of pet stores). Retails for about $30 and covers pH, ammonia, nitrates and nitrites.

I've found that my pH readings vary widely (6.4 -> 7.2 across two seperate test tubes done at the same time). I suspect this is due to the test tube not being completely dry or something and I'll look to be more "scientific". However, I am also mildly color blind :-) and the variations between, say, 6.6 and 6.8 is pretty difficult for me to discern. That said, the differences I am seeing - again using two tests at the same time - are from yellow to a pretty dark blue. So that's easy to see :-)

With this in mind, I am considering splashing out on an electronic pH tester. Aside from a more distinct reading (a number vs. a color) can I be sure that these are accurate? I've seen references to these around these forums and the Hanna testers seem pretty well respected. But, having spent $1,000+ in the past 10 days or so getting all my stuff I am now reaching the point (or, more accurately, my wife is!!) where I need to be somewhat more disciplined about what I buy :-)

Can anyone point to a cost effective, reliable and accurate electronic tester? Oh - and would the variations I am seeing be explained simply "residue" in the test tubes - the differences seem pretty significant, which is why I am somewhat intruiged by this.

Thanks.

Mark

[drayman86]

pH is a pretty important parameter to keep track of with discus. I'm very thankful I had/have a reliable pH meter that gives direct reads of tank pH. I was able to spot severe pH crashes in my system shortly after I added fish, and corrected the problem.

Here's what I use. With a set of calibration solutions, total cost was about $100.

http://www.automatedaquariums.com/mw_m100.htm

The probe is the expensive part of the meter, and doesn't last forever. With proper storage, however, it should last at least 18 months. The key to extending the life of the probe is storing it in the "boot" that comes with the meter. Keep the "boot" filled with low pH solution (I use the 4.0 calibration solution) when the meter is not in use. If the probe dries out, it's likely fried.

[Butch]

Hi Mark....just to give you a choice, I use the Pinpoint ph and also
a conductivity meter. I have had no problems except my letting the
probe dry out one night. I now leave my hanging in one of my tanks
until I use it. Here's the link:

http://www.usainstrumentation.com/en-us/dept_102.html

Butch :)

[markwill]

Thannk you both - much appreciated. So, excuse my ignorance, but how are the calibration solutions used? Are they used every time or every few uses? I guess the real quetion is typically how often would I need to buy new supplies?

And why are there calibration solutions for different pH's - I'm obviously making a poor assumption that a single solution (regardless of pH) sets the "base" against which the water is compared.

I almost understand this :-)

Thanks.

Mark

[BigDaddy]

If you leave the probe in the tank full time, you'll have to calibrate less often.

"Good" pH monitors have a two point calibration system. They are more accurate (mostly) than systems that only calibrate against one solution.

You typically want to use the solutions that are closest to your pH range. For Discus, that typically means the 4.0 solution and the 7.0 solution (acid to neutral), as opposed the the 7 & 10 combo

[Butch]

Mark...I calibrate mine about once a week or maybe every 5 days.
I buy the pint bottles of buffer, 4.0 and 7.0, for about 8.00 bucks
each and they last me several months. I use two shot glasses to
put the buffers in when I calibrate, just enough to cover the end
of the probe. I bought a new probe not too long ago and it was
about 47.00.
On ph, a meter is the way to go, but I still run a test kit ph every once
in a great while just to keep the meter honest. I am paranoid about
test equipment, I get it from my everyday job at Shell.

Bert :)

[aggie_67]

Mark,

Real question is why do you feel you need a ph meter? Understand there are those who need it, low buffering capacity water, etc. but IMO for the average hobbyist using a constant water supply (big city, well water, etc) which has sufficient buffering capacity, it may not be necessary. Discus will grow in a wide range of ph with no problems as long as it is constant. I have looked at adjusting my ph but the downside of it bouncing back, etc (being unstable) more than outweighed the advantage of low ph.

[markwill]

Mark,

Real question is why do you feel you need a ph meter? Understand there are those who need it, low buffering capacity water, etc. but IMO for the average hobbyist using a constant water supply (big city, well water, etc) which has sufficient buffering capacity, it may not be necessary. Discus will grow in a wide range of ph with no problems as long as it is constant. I have looked at adjusting my ph but the downside of it bouncing back, etc (being unstable) more than outweighed the advantage of low ph.
That's a good question - and one I have been considering. See the following thread I just created:

http://forum.simplydiscus.com//showthread.php?t=44259

I'd love your opinions :-)

Thanks.

Mark