PH probe

[SPC]

Hi Randy, a while back you mentioned some good PH probes that could be purchased, I have done a search but cannot seem to locate this thread. I have a Pinpoint meter but would be interested in a more durable (one I don't have to calibrate as much) probe. Would you mind sharing this info again please?
Thanks,
Steve

[Randy Holmes-Farley]

Steve:

I've never used a Pinpoint. The probe is removable with a connector like a BNC?

I'd buy a permanently filled (likely gel filled) electrode. Reasonable ones are $50-150. Better (more expensive) electrodes just aren't worth it for a reef keeper. The drawback with fillable probes, which are often of higher quality, is two fold, but both relate to accidents.

1. If a fillable probe drops into the water so far that tank water enters it, you'll have a mess inside that may not be easy to clean out.

2. If a fillable probe dumps its fluid to the tank, you might add undesirable ions to the water, depending on the type of electrode used.

Cole Parmer is a good source.

[andy-hipkiss]

Randy,

FWIW, I have used a number of probes over the years and the ones that Tunze supply (which are refillable) are the ones that have lasted the longest. The first one lasted over 2.5 years before it when ga-ga. I still have it as a spare having reconditioned it.

I would have preferred to not buy an aquarium branded model, but the price is not significantly more in this case and the longevity is far better. For example my original pinpoint probe only lasted about 13 months IIRC. A Hanna general purpose gel type was useless after 6 months.

Admittedly, when I phoned up my lab supply place one time looking for a suitable probe, after much head scratching they recommended the same as you. Dunno what is "special" about the Tunze ones (if at all), but they do seem to work better.

(quickly touching wood, since having said all this, my current probe will probably die after 12 months ;) )

[Randy Holmes-Farley]

Andy:

Thanks for chiming in!

I'm not sure what goes wrong with typical pH probes in a reef tank, and it's hard to know if the real cheap probes are worth it or not.

One of my oldest probes (a gel type) is just getting to the point where it won't calibrate well (needs too low of a slope for the meter to allow), but it is more than 9 years old and has been sitting in tank water for the last six.