# Testing ph



## mr. luke (9 Sep 2014)

I have a 2 point calibration ph pen which seems pretty terrible, it looses calibration almost instantly.
How accurate are liquid tests for ph?
At the minute im taking my water into the lab at work but its not too practical 
This is for a shrimp project which is the only reason im concerning myself with water parameters.
Thanks in advance


----------



## dw1305 (9 Sep 2014)

Hi all, 





mr. luke said:


> I have a 2 point calibration ph pen which seems pretty terrible, it looses calibration almost instantly. How accurate are liquid tests for ph?


 You should really calibrate your pH probe with the pH4 and pH7 buffers before every use. If the probe has been stored dry etc. it will be knackered and you need a new one. 

I had to buy a replacement for one of our "cheap and cheerful" soil pH meters today which was £320 for the meter + £120 for the probe + VAT. 

Liquid tests are fine as long as you just need a pH range. If you water is low conductivity you may struggle to get a consistent reading. 

A specific indicator for the range of pH values you are interested in would be better than a universal indicator that does a wider range.

cheers Darrel


----------



## mr. luke (10 Sep 2014)

Thank you Darrel 
The water is hovering around 100tds at the moment. Will this impact a liquid test kit or just the probe type kits?


----------



## dw1305 (10 Sep 2014)

Hi all,





mr. luke said:


> The water is hovering around 100tds at the moment. Will this impact a liquid test kit or just the probe type kits?


 No, it should be fine for the pH meter. It may tak a bit longer to stabilise than it would in "saltier" water.

cheers Darrel


----------



## mr. luke (10 Sep 2014)

Sorry I should have read your earlier reply properly 
I think ill stick with my ph pen and testing at work for accuracy


----------



## PARAGUAY (19 Sep 2014)

Hi Luke just seen your post, I use liquid tests with a API kit but as with other tests if I doubt my results my LFS do tests ,they are good if you have a good LFS Its reassurance


----------

