pH/TDS meter

[DavidCampen]

Originally Posted by Discus

Get one that does combo pH, TDS and temperature, that way it stays fairly accurate no matter what the temperature. The model I link to in my earlier post does this.

Yes, that is a nice combination meter; and you are also paying an extra $100+ for the pH function - $150 for this combination meter vs $15 for a TDS only meter.

Also, read the reviews here for the combination meter:
Amazon.com: Customer Reviews: Hanna Instruments HI 98129 pH, Conductivity, Tds, Temp Tester

Note the reviewers who comment that a pH meter is a high maintenance device. The pH sensitive membrane needs to be stored bathed in a buffer solution so that it won't dehydrate and then rinsed with RO water each time before use. The one reviewer who was complaining that he had tried 2 of these meters and neither would hold pH calibration probably did not understand and employ the correct protocol for storing a pH sensitive membrane.

For now, I use pH indicating paper as an inexpensive alternative to a pH meter.

[Brotherly Monkey]

I have a soil stick from Spectrum technologies that I like a lot, and a Hanna TDS meter that's adequate. I think the model number is "HI 98311" on the TDS meter

The probes on the soil stick last from 4-6 months, but I generally replace every four

[Brotherly Monkey]

Originally Posted by DavidCampen

Yes, that is a nice combination meter; and you are also paying an extra $100+ for the pH function - $150 for this combination meter vs $15 for a TDS only meter.

Also, read the reviews here for the combination meter:
Amazon.com: Customer Reviews: Hanna Instruments HI 98129 pH, Conductivity, Tds, Temp Tester

Note the reviewers who comment that a pH meter is a high maintenance device. The pH sensitive membrane needs to be stored bathed in a buffer solution so that it won't dehydrate and then rinsed with RO water each time before use. The one reviewer who was complaining that he had tried 2 of these meters and neither would hold pH calibration probably did not understand and employ the correct protocol for storing a pH sensitive membrane.

For now, I use pH indicating paper as an inexpensive alternative to a pH meter.

I'm far from an expert, but I'm pretty sure all PH meters are high maintenance. It's just a big flaw in the design, and where there is no real alternative circuit

[DavidCampen]

Here is a cheap ($15) pH meter:
FS pH Meter for plants - Orchid Board - Most Complete Orchid Forum on the web !

I have seen the same things listed on Amazon.

I don't know what the mechanism is for these but I strongly doubt that they work with any accuracy.

[Brotherly Monkey]

When I was first in the market for a meter, I bout the type they sell out laws, with the similar needle gauge, but with a solid pin, and it amounted to a waste of money, IMO.

If you're trying to save cash, just get some litmus paper