Every time I see a picture of someone using a handheld TDS meter, they’ve got it dunked in a glass of water. Why is that?
I just fill up the end cap with water and stick in the meter.
They do it for the same reason I used to do it. The bell has just not went off in their head yet.
At first I used fresh clean plastic cups but one day the bell went off in my head and I saw the end cap as the water testing container.
It wouldn’t be my method. From my days of testing swimming pools, you usually find a better reading by going quite deep up to your elbow before taking a sample. Because of impurities in the cap I would go for a larger vessel as you can to test the water. Sometimes not always possible, but you’re right - most ad’s featuring the handheld tester are done shown using a tumbler or glass. Maybe to prove that it’s actually being dipped in the water & not thin air 
I just ordered one from wcr to use with my ultrasonic and wfp. I will test in the cap and with the ultrasonic tank to see if there is a differance.
I’m really crazy about checking TDS. I check before every job, and throughout the course of the job. Part of it is curiosity, the other part is to make a scene about it in front of my customers, besides the fact I want pure water.
The other crazy thing I do is I rinse the cup out 3 or 4 or 5 times, even before i measure the “before” water from the tap. I want to make sure the reading is accurate. I usually find that there’s a point or two difference in readings if I skip this step. I also rinse the part of the TDS meter that is submerged so it doesn’t contaminate the water. lol.
So I just keep the meter clipped to the cup. The cup is probably easier to rinse out then the cap. I would imagine rinsing the cap out would spray water at me. I thought the cap just protected the probes. Now I know what to do if I lose the plastic cup though.
I didn’t strike me yet that you could use the end cap. Good to know.
I kinda like my old-mangled porcelain mug though. It might take me a while to switch over as I can get sentimental about those tools that I’ve had for some time.
The end cap works fine. I rinse it thoroughly before testing. The cup is clean, the cap is clean, it’s the same water you’re testing…if you get 000 that’s all that matters.
If my tank is good I always get 000 whether testing with a thoroughly rinsed cup or the thoroughly rinsed end cap.
Why bother testing? Get an output reader on your setup. I was testing last year, every place I used my machine. Then I sat back I thought why? As long as my output read under 10 I could careless if the place has 10000000000000000 tds. I have not taken out my tds meter for window cleaning once this year. My wife uses it more for mixing her chemicals for growing her plants.
After 10 years, I finally got one last year. I only check the output from my 2 di tanks every now and then. I can actually smell my water from my tanks, especially a set of fresh tanks.
[COLOR=“Red”]
I LOVE THE SMELL OF DI WATER IN THE MORNING![/COLOR]
BTW guys I found my instructions in my basement the other day for mine and started to read it. I would not put it in the cup. States that the thing is not water proof and should not be sunk below the tester end. Could damage the thing. When I was using mine I used the end cap. But that’s how I saw it done the very first time by Chris so I figured thats how it is done. I also read that it said to wipe the end off with tissue. I had no idea as I thought the end was a sensitive thing not to be touched. Oh well live and learn.
That’s right Ray - hope I didn’t give the impression to go elbow deep into your pure water containers! I was talking about swimming pools.
Last thing you want to do is contaminate the water with arm hairs & sweat glands & also is ain’t much good for your skin.
