pH test inaccuracy

[TomCruise]

After much deliberation with my scientist and her supplier rep.  The following pen tester has been vetted and recommended.  http://www.e-lspi.com/hana-ph-meters-1-1-1-1-1-1 It can be purchased from amazon here: http://www.amazon.com/gp/product/B0085WV6GM/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944687622&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B002NX0VY2&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0F96SFAN0TDTEH5RQ4S4

 

It is the Hanna Instruments HI98128

 

It looks like it has been recommended in other forums as well.  I feel confident in my purchase and will update my experiences.  It has a replaceable electrode as well. 

[fishlover]

After much deliberation with my scientist and her supplier rep.  The following pen tester has been vetted and recommended.  http://www.e-lspi.com/hana-ph-meters-1-1-1-1-1-1 It can be purchased from amazon here: http://www.amazon.com/gp/product/B0085WV6GM/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944687622&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B002NX0VY2&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0F96SFAN0TDTEH5RQ4S4

 

It is the Hanna Instruments HI98128

 

It looks like it has been recommended in other forums as well.  I feel confident in my purchase and will update my experiences.  It has a replaceable electrode as well. 

I read the reviews at Amazon. This tester needs to be calibrated each use to keep the accuracy. How can you do it when you have multiple tanks to test?

[TomCruise]

Hmm... That would not be good.  If this is the case I will send the thing back and post my experiences. 

[TomCruise]

Ouch those are not good reviews.  The search continues!!

[Shrimpy Daddy]

I read the reviews at Amazon. This tester needs to be calibrated each use to keep the accuracy. How can you do it when you have multiple tanks to test?

 

Every single pH probe has to be calibrated every time when you take it out of the storage liquid for accuracy, not just this particular one. (^_^")y

 

Usually the storage liquid is very acidic. Hence, what you should do is to flush it in tap water for 30 - 60 sec, then put the in a cup of tap water for a few minutes to let all the H+ ion neutralised. Lastly gently shake it dry before use.

 

We are not using it for laboratory testing, thus we don't need high accuracy. As such, we don't need to re-calibrate every time we use. 

 

I saw that there are some discussions about Pinpoint. I would like to chime in my experience. Out of so many brands of probe I used before, Pintpoint has the least lifespan. Not sure is it because of it is a single terminal electrode.

 

When you are searching for pH probe, look for the following two aspects:

1. Replaceable probe
2. Dual terminal (which means it is still usable even the internal liquid level to fall till very low.)
3. Calibration method is digital. Analogue method (use a screw driver to adjust) is a real pain. Digital method takes you very little effort and is very pleasing to do it.

Lastly, always calibrate your new pH probe/ pen. All new probe/ pen is not calibrated.

[TomCruise]

Hey Shrimpy.  Mind if I ask what you use?

[Shrimpy Daddy]

Currently for aquarium, I am using pH probe (not pH pen) connected to my GHL Profilux controller. I used to use GHL's pH probe. They are very lasting (can be used for 2 years plus) and reliable, but they are very expensive. Hence, I had switched to Hanna probe. Some of my tanks are using Hanna probe for almost 2 years. For the rest of my probes (ORP, Temp and Conductivity) are still using GHL one.

[TomCruise]

This!

http://www.amazon.com/gp/product/B00023RYQ8?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

 

Specifically a:

Extech PH100 ExStik 0.00 to 14.00-PH Waterproof Meter

Just got it and so far it's great.  I've used it for a day and will post updates.  It auto calibrates (with calibration solution) Tells you when it needs calibration and has a replaceable electrode. It also tells you when it's time to replace it.  It's got the highest reviews I've seen and gets the nod from my scientist.