# What is the best/worst replacement PH probe?



## Smokin_Cache (May 22, 2006)

Would like to know the experts thoughts on the best replacement probes.

Being an instrument tech. the probes sold as aquarium probes look less than great. But PH is one of the easiest things to measure. Are all probes created equal? I don't think so. I have seen probes last well over two years in continuos service (waste water) with monthly clean/cals.

What's your opinion?

Thanks


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## Salt (Apr 5, 2005)

They all pretty much get the job done. There are literally dozens of models to choose from, take your pick:

http://www.coleparmer.com/catalog/product_index.asp?cls=3528&Request=category

The more expensive ones mainly do three things:

- React to changes in pH quicker (seconds as opposed to more seconds or minutes)

- Last longer (A few years as opposed to less than a year)

- Don't have a tendancy to get clogged and therefore require less periodic cleaning


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## yxberia (Apr 19, 2005)

Sorry for interrupting, my question is a bit out. 
I like to know how long can a pH probe lasts ?
Or should I wait until the reading is not accurate ?


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## yxberia (Apr 19, 2005)

Salt said:


> They all pretty much get the job done. There are literally dozens of models to choose from, take your pick:
> 
> The more expensive ones mainly do three things:
> 
> ...


How can we tell if a probe is of better quality than others ? My LFS just told me there are 2 types from Taiwan and US available. They always claim US made has higher quality. Of course US one is more expensive but doesn't mean that Taiwan made is not usable ? How to tell ?


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## werner (Jul 6, 2006)

?


> I like to know how long can a pH probe lasts ?
> Or should I wait until the reading is not accurate ?


I have been using the American Marine pH probes (I use their Pinpoint pH controller.)
From what I understand, these will last about 18 months-2 years. I believe this includes shelf life as well as actual working time, so buy from a store that has more frequent turnover. Once it won't read/calibrate quickly, it's time for a new probe. I've heard that calibrating should be done anywhere from every 6 weeks to every 90 days.


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