Word of warning - TDS Meters

[Chris34]

Just a word of warning regarding checking your TDS meters.

My RO system is set-up with two small resin canisters , I think they're 10 inch or something like that. I've opted to do it this way as I like the idea of changing the resin on one of them more frequently than say once every year, just to keep everything clean and not allow bacteria to be breeding inside etc (I have found bluebottles housing inside the larger canisters in the past).

Anyway usually, I've not timed it as such, but usually the TDS starts to creep up about once every month. As soon as it hits 1ppm then I change once of the 10" canisters and replace with new resin.

I check the TDS every night when I'm producing the pure, every single time I'm producing I check it at the start and check it when my water butt is full and I've finished making the pure, this is checked directly from the ro (not the water in the water butt).

This morning I was producing a bit more water and checked it as usual, it read 0ppm. Now I've been thinking that for the past few weeks that it must be due to be changed very soon as it seems a long time since I last had to change it, but as I say I don't log how long it was since I changed it. So this morning I thought I would just go and check the tap water in the house to see if it was softer than in the summer which would explain why I'm getting much longer use out of the resin. So filled a mug from the kitchen tap, dunked the tds meter in there and... 0pppm I double checked it, triple checked it, took the batteries out, replaced them, gave it a tap, did everything but it didn't budge above 0pppm.

I've no idea what my water now is. Obviously I've ordered a new tds meter but just a word of warning, double check your water all the time just in case the meter fails. From now on I'll be having a second container with tap water in it that I use to check the TDS meter daily.

I didn't expect one to fail like this. I thought it might give incorrect readings but not something like this where it shows as zero all the time. Easy to get complacent with things like this, so just a warning to others who do as I've done ?

 

[Mattlekim]

This is why I have 2. I have an inline one on my filters, and a handheld one. I double check once a month to make sure nether has failed.

 

[Pjj]

Just a word of warning regarding checking your TDS meters.

My RO system is set-up with two small resin canisters , I think they're 10 inch or something like that. I've opted to do it this way as I like the idea of changing the resin on one of them more frequently than say once every year, just to keep everything clean and not allow bacteria to be breeding inside etc (I have found bluebottles housing inside the larger canisters in the past).

Anyway usually, I've not timed it as such, but usually the TDS starts to creep up about once every month. As soon as it hits 1ppm then I change once of the 10" canisters and replace with new resin.

I check the TDS every night when I'm producing the pure, every single time I'm producing I check it at the start and check it when my water butt is full and I've finished making the pure, this is checked directly from the ro (not the water in the water butt).

This morning I was producing a bit more water and checked it as usual, it read 0ppm. Now I've been thinking that for the past few weeks that it must be due to be changed very soon as it seems a long time since I last had to change it, but as I say I don't log how long it was since I changed it. So this morning I thought I would just go and check the tap water in the house to see if it was softer than in the summer which would explain why I'm getting much longer use out of the resin. So filled a mug from the kitchen tap, dunked the tds meter in there and... 0pppm I double checked it, triple checked it, took the batteries out, replaced them, gave it a tap, did everything but it didn't budge above 0pppm.

I've no idea what my water now is. Obviously I've ordered a new tds meter but just a word of warning, double check your water all the time just in case the meter fails. From now on I'll be having a second container with tap water in it that I use to check the TDS meter daily.

I didn't expect one to fail like this. I thought it might give incorrect readings but not something like this where it shows as zero all the time. Easy to get complacent with things like this, so just a warning to others who do as I've done ?

I have never experienced this but have heard others say this we have two TDS meters and use both to double check readings just in case .

 

[JohnDoeWindows]

Not to hijack your topic or anything, but on the subject of PPM does anyone know if your pre filters cause a rise in ppm if you don't change them frequently enough? I know that it damages your membrane etc

 

[Dave B]

I harvest rainwater nowadays and have 2000l storage in my garden and rarely have to produce water
My extension roof and other roofs are all plastic and never bother to check tds as always keep them clean
Rainwater off my roofs is always under 2 so don’t bother
If rarely I am running short I use spotless to top up but only about once a month
Worth swapping roof tiles for plastic when the roof gets too old as I can fill 2000l with a decent days rain under 2ppm
Sheets better than ro water also

 

[Dave B]

Not to hijack your topic or anything, but on the subject of PPM does anyone know if your pre filters cause a rise in ppm if you don't change them frequently enough? I know that it damages your membrane etc

Pre filters won’t make a difference only affects the life of your membranes

 

[spruce]

Not to hijack your topic or anything, but on the subject of PPM does anyone know if your pre filters cause a rise in ppm if you don't change them frequently enough? I know that it damages your membrane etc

A sediment filter that is restricted with sediment will reduce the amount of water available to the r/o membrane/s. The result is that with reduced flow, your water pressure on the membrane/s reduces, making the membrane/s less efficient. So yes, that will result in an increased ppm on the pure leaving the membrane/s.

Our water pressure is 55psi ATM. When the sediment filter starts to get blocked with sediment, the pressure after the prefilters can drop to 40psi. The pure tds then rises from around 3ppm to 5ppm. While that's not a train smash, it basically means my resin usage will be roughly 60% more if left.

A Carbon block filter removes chlorine from your tap water. But it has a finite service life. If the carbon filter isn't changed regularly, it will allow chlorine to pass through it. Chlorine eats away at membrane material, making those microscopic holes bigger, pushing up the tds of the pure being produced.

 

[Dave B]

I removed part of my garden fence to make parking for my van and have 2x 1000l ibc’s out there so always have water
Have hose running from the patio to the back buried under the flower beds so not intrusive

 

[Chris34]

I harvest rainwater nowadays and have 2000l storage in my garden and rarely have to produce water
My extension roof and other roofs are all plastic and never bother to check tds as always keep them clean
Rainwater off my roofs is always under 2 so don’t bother
If rarely I am running short I use spotless to top up but only about once a month
Worth swapping roof tiles for plastic when the roof gets too old as I can fill 2000l with a decent days rain under 2ppm
Sheets better than ro water also

I'm surprised you get enough to keep you going. Around here I'm getting wet everyday at the moment, for the last 3 weeks I could probably fill a swimming pool with the amount of water falling on my head ? But in all seriousness in the summer, in particular the early summer it can barely rain for about 6 weeks.

I suppose it depends how big your roof is as well. I do have a brook at the back of mine and could probably fill an ibc tank in seconds from the water from that... but i expect the ppm would be a lot higher than rainwater... also might end up with a few fish and frogs in the ibc

 

[Chris34]

I have never experienced this but have heard others say this we have two TDS meters and use both to double check readings just in case .

It's took me by surprise, I didn't expect it to fail in this way, I thought the reading might go out or it might just not turn on, but to just constantly read zero... I didn't think that could happen. Lesson learned.

Out of interest, I didn't have time to look earlier so just got the HM3 one again, does anyone know if there any that are better than this one? Like are there any that measure to the nearest 0.1ppm instead of 0,1,2 etc.

 

[Mattymarske]

If you've got the inclination to plumb these into your system they're well worth the investment. I've got 3 so 6 TDS readings on my van mounted system.

Changed the resin vessels yesterday and I was kicking myself for not having the prefilters ready to swap over as well. Ordered pack of 12 last night so hopefully here tomorrow to swap over. Back to 0 TDS out of the brush head. Last week was 7/8 wed-thurs. It's been 4ppm for about a month and a half but no issues with spotting - it's been that wet up here it probably wouldn't show up anyway!


Last resin change was 2nd November 2022 so used the 2nd half of the bag yesterday. (Kept in airtight/dark container.)

 

[scottish cleaning service]

I got told to buy an HM Digital not sure why.

HM Digital TDS-3 water testing TDS meter with leather carry case

Compact pocket sized water testing meter, HM Digital TDS-3

www.waterfilterman.co.uk

 

[Dave B]

I'm surprised you get enough to keep you going. Around here I'm getting wet everyday at the moment, for the last 3 weeks I could probably fill a swimming pool with the amount of water falling on my head ? But in all seriousness in the summer, in particular the early summer it can barely rain for about 6 weeks.

I suppose it depends how big your roof is as well. I do have a brook at the back of mine and could probably fill an ibc tank in seconds from the water from that... but i expect the ppm would be a lot higher than rainwater... also might end up with a few fish and frogs in the ibc

Just my polycarbonate patio roof is 6x4 metres
Plus 2 sheds and next doors patio roof which I keep clean
1 rainy day tends to fill the ibcs
In mid summer I do need spotless but most of the year I’m fine

 

[Chris34]

What do you reckon? Looks like a fake to me. Original on the right that I got about 5 years ago, new one on the left supposedly HM Digital. Bought from a reputable supplier, just under £24 delivered.

 

[scottish cleaning service]

I took delivery of a

Hofun TDS Meter Digital Water Quality Tester, TDS, Temperature & Conductivity Meter 3 in 1, 0-4999 ppm and I have the same as your HM Digital meter.​

Checked a cup of water and the Hofun was 63 and HM was 66 so only 3 of a difference. Probably somewhere in the middle is the exact reading.

Glad someone mentioned it, because we should always have 2 or 3 meters to check from.

 

[ched999uk]

All the images I can see have the HM logo on the measuring end! Looks iffy.

 

[Mattlekim]

One other thought..get some testing fluid. You can always check every now and again if you TDS meter works..you can also calibrate it's as they can deviate a few ppm after a year or so.

 

[ched999uk]

One other thought..get some testing fluid. You can always check every now and again if you TDS meter works..you can also calibrate it's as they can deviate a few ppm after a year or so.

Can you only buy 1 tds value of calibration fluid? If so then it's not that useful as you can only calibrate a single value and it's a relatively high one. Ideally we need a zero then say a 50tds so when you adjust the trim you know you are getting the zero and a 50tds point correct. The ones I have seen are about 342tds so not really in the range that we need accuracy in. Still better than nothing though.

 

[Mattlekim]

Well the way that they work is with a baseline of 0. Using a high ppm fluid allows for more accuracy.

 

[Pjj]

If I bought it from a reputable dealer at that price and thought it was a fake I would give them a ring and diplomatically express my concerns and see what they had to say . Out of interest what’s the readings like compared to the original one ?..

 

[scottish cleaning service]

What do you reckon? Looks like a fake to me. Original on the right that I got about 5 years ago, new one on the left supposedly HM Digital. Bought from a reputable supplier, just under £24 delivered.

Yes, I have the one on the right, other looks bizarre.