TDS Meters

[mnace91]

Hello,

I just started up my RO system again after a year of sitting. I was a little worried about the quality of the filters but I didn't want to just buy them if I didn't need to. So I did a half hour flush and then took a sample of the water to my lfs to be tested. his handheld TDS meter showed 2ppm and he said it should be safe to use on my tank. I am currently using the water but I would like to buy my own TDS meter to keep track of the filter quality. does anyone have any brands that they prefer? the two im looking at are on bulk reef supply. one is a dual inline reader and the other is a handheld.
Dual Inline TDS Meter DM-1 - HM Digital - Bulk Reef Supply


TDS-3 Handheld TDS Meter - HM Digital - Bulk Reef Supply

the one my lfs uses and recommended is on ebay.

Digital LCD TDS Meter Tester Filter 0 9990 ppm Water Quality Purity Test Set | eBay

it is a lot cheaper... but I'm worried about the accuracy and would rather spend more money on something that will last.

 

[AZDesertRat]

Stick with HM Digital. I always recommend a good ATC handheld since the inlines are not truly temperature compensated so lack the accuracy of the handheld which all good ones are ATC compensated. For around $20-$25 you can get the TDS-3, TDS-4TM or the newer AP-1, all are very similar .
Meters and Controllers - Handheld Meters - Buckeye Hydro

I use the COM-100 myself and like the additional sensitivity since it reads down to a tenth of a TDS versus 1 TDS resolution and can be used to measure electrical conductivity as well as TDS.

There are many knock off meters on ebay but I wouldn't bite if I were you. If it doesn't say HM Digital or Milwaukee Instruments or some other well known brand name I wouldn't buy it, they are copies or clones and not the same quality.

BTW, I do have two of the HM dual inlines but I never even turn them on anymore since they never agree with my COM-100, AP-1 or TDS-4TM handhelds which ar all very close to each other. The inline actually senses air temperature, not water temperature and they are rarely the same so has built in accuracy issues. It can be off as much as 1%-2% of full scale for every degree C the air and water differ so can be quite significant on the low end where it counts.

 

[mnace91]

I think I'm going to stay away from the inlines now that you say that. I also like the looks of the COM-100. might spend a little more and just get that. Thanks for the suggestion.