info on measuring pH in DI water

[DJ88]

Well I did some reading after a comment was made that something was wrong with my RO/DI as my pH readings from my meter were high.

Well after sitting down over several days and measuring the effluent from my RO/DI with the DI on and bypassed, I have been doing some additional research.

In fact it turns out that with the equipment we as hobbyists use we cannot accurately measure the pH of DI water.

A pinpoint meter operates by measuring the electric potential(voltage difference) between two different sensing electrodes. One which is sensitive to H+(Hydrogen) Ions and a reference electrode. If we run our water through a De-Ionizing resin what is there to measure? Nothing.

Keep this in mind those of you using a Pinpoint meter. If you measure your RO/DI water for pH it will show erratic numbers. Over a period of an hour I watched mine swing from 8.3 to 10 to 6.2 to 8.9.

Well my curiosity is satisfied and I wanted to share.

Once again. this is with a pinpoint meter. Not solutions.

Hope others find that interesting. I sure did. I had remembered that a meter couldn't properly measure DI water but not why. Now I have a better idea.

If you want to know more.. go visit this site.
ph-measurement.co.uk

[ 14 January 2002: Message edited by: DJ88 ]