[pylofm]

Hi...I have recently fitted a RO-MAN pump and a HM TDS 2 inline meter....

Now....

2x HM tds handheld meter - both read 178 from the tap (in a container)
1x HM tds 2 meter reads 178 (from same tap) water not running but within the loop.

When water is run through the pump TDS reading drops to around 140 - 150 depending.

I seem to get 000ppm indicated prior to going into the 700ml DI vessel and my Good product water is 46.26% and my waste water 53.73 % volume so not bad and at 25c I would generate 806 (+/-) litres of good per 24 hours...

So my question is would anyone know why the TDS readings would change with the water flowing?

Thanks
Dave.

[KarlJones]

To emulate this is best as I could I took my handheld TDS meter and stuck in a container, the tap water read 240 TDS.
I then ran the tap full power and held the TDS meter underneath, the TDS read 25 (obviously a very false reading).
Slowly I tuned down the tap and eventually managed to get a reading of 200+ TDS.

What seems to be happening is this, and someone will correct me if I get things the wrong way round.

The TDS meter measures the "lack" of resistance, so if water has a high amount of dissolved solids then it conducts better.  Moving water it seems does not conduct as well as still water.

I suppose it is like trying to cross a river, the faster it flows the harder you have to work to get to the other side.  It seems to be the same for electricity.
 

[pylofm]

Thanks for the answer and thanks for taking the time..