Single bed DI

[KJoFan]

So I just started using the single bed/triple DI setup from BRS. I made 50 gallons of product water last night and here’s what my trains look like afterwards.

Anion took a hit:

Does this tell me my source water is high in CO2?

 

[redfishbluefish]

Little more info.....what's the source of your raw water? If it's a well, there is more likelihood of a CO2 problem....and you can test for this using a pH meter. Take raw fresh drawn water and measure pH. Bubble this water (or let sit over night) and measure pH again. If it goes from an acidic pH to a more basic pH, it's a CO2 problem. If no pH change, it's not CO2.

 

[mfinn]

So I just started using the single bed/triple DI setup from BRS. I made 50 gallons of product water last night and here’s what my trains look like afterwards.

Anion took a hit:

Does this tell me my source water is high in CO2?

I'm assuming you used a single mixed bed di resin before.
How much water did you get out of a single canister?

 

[chipmunkofdoom2]

I use this setup also and my anion bed is almost entirely depleted. The other two resins show almost no change at all.

Your depletion sounds rather fast, but the anion will likely always deplete faster than the other two beds.

 

[KJoFan]

Source is municipal water, but origin is well water, if that makes sense. I live in a very small municipality with little to no water treatment occurring. Water is quite hard and iron laden though I don't have specific numbers to share on that.

As for how many gallons I was getting out of mixed bed previously....in a dual mixed bed setup I would guess around 150 gallons.

RO/DI overall is 150gpd unit, being two 75gpd membranes.

 

[KJoFan]

Water does go through the water softener prior to the RO/DI unit as well.

 

[mfinn]

As for how many gallons I was getting out of mixed bed previously....in a dual mixed bed setup I would guess around 150 gallons.

So if you get more than 150 gallons of clean water out of the Anion canister it will be worth it.

 

[KJoFan]

So if you get more than 150 gallons of clean water out of the Anion canister it will be worth it.

Right, I'm not complaining, though I was surprised at the depletion from just 50 gallons of product. But, the whole point of switching to single bed was to maybe save a little $$ as I was switching even my dual DI fairly frequently (every couple months give or take) so at this rate it would seem that the cation will last awhile as well as the mixed bed at the end as after the first two stages it's reading 0 tds.

 

[KJoFan]

Though, knowing me I'll let the anion deplete a little too much and rely on my mixed to pick up the slack before I swap out. maybe that's not the correct approach?

 

[mfinn]

Though, knowing me I'll let the anion deplete a little too much and rely on my mixed to pick up the slack before I swap out. maybe that's not the correct approach?

Since that's the canister that gets used up the fastest, I'm assuming you have a TDS meter probe right after it?

 

[KJoFan]

The setup from BRS out of the box has a triple tds meter on it. First reads from membrane into the DI unit, second reads after the cation and anion stages and the third reads after mixed bed.

 

[mfinn]

The setup from BRS out of the box has a triple tds meter on it. First reads from membrane into the DI unit, second reads after the cation and anion stages and the third reads after mixed bed.

Hmmm. So you can tell when the water going into the mixed bed canister has a tds of more than 0.

 

[KJoFan]

Hmmm. So you can tell when the water going into the mixed bed canister has a tds of more than 0.

As I understand it, yet. I think I read somewhere from BRS that checking TDS after each single stage didn't really do much, as ions are changing/moving and can affect TDS readings so reading after cation stage only isn't helpful? That's my recollection in a nutshell. So, they only put in a checkpoint after both single stages. But, I suppose that begs the question, how do you know when the cation stage is depleted, aside from color?

 

[Randy Holmes-Farley Verified Community Expert]

As I understand it, yet. I think I read somewhere from BRS that checking TDS after each single stage didn't really do much, as ions are changing/moving and can affect TDS readings so reading after cation stage only isn't helpful? That's my recollection in a nutshell. So, they only put in a checkpoint after both single stages. But, I suppose that begs the question, how do you know when the cation stage is depleted, aside from color?

In a single bed DI, the TDS will rise after the first one it encounters.

 

[turfster26]

In a single bed DI, the TDS will rise after the first one it encounters.

I run the same exact setup and that was my understanding too. I only have a dual TDS meter and measure after the Anion and Mixed Bed; not after the Cation.

I just set it up a week or so ago and I'm hopeful to get some extended use out of each stage. I've been running a dual stage mixed bed DI for many years and always burnt through them every 6-8 weeks. Only time will tell how efficient the new setup will be. The good thing is it was little dollars invested to try something a bit different.

 

[KJoFan]

In a single bed DI, the TDS will rise after the first one it encounters.

Also my understanding from reading. Still begs the question of how one knows when the first stage, cation in this case, is depleted? Since tds meter is only reading before DI, after the first two stages, and after mixed bed... If TDS starts to rise after the first two stages you wouldn't be able to discern which stage is depleted necessarily unless you base it solely off of color change as I said. But, as we know color change is not always 100% accurate either. Maybe I'm overthinking it?

I run the same exact setup and that was my understanding too. I only have a dual TDS meter and measure after the Anion and Mixed Bed; not after the Cation.

I just set it up a week or so ago and I'm hopeful to get some extended use out of each stage. I've been running a dual stage mixed bed DI for many years and always burnt through them every 6-8 weeks. Only time will tell how efficient the new setup will be. The good thing is it was little dollars invested to try something a bit different.

I too am hoping for a bit more efficiency/extended use. I hope you see the same!

 

[Randy Holmes-Farley Verified Community Expert]

Also my understanding from reading. Still begs the question of how one knows when the first stage, cation in this case, is depleted? Since tds meter is only reading before DI, after the first two stages, and after mixed bed... If TDS starts to rise after the first two stages you wouldn't be able to discern which stage is depleted necessarily unless you base it solely off of color change as I said. But, as we know color change is not always 100% accurate either. Maybe I'm overthinking it?


I too am hoping for a bit more efficiency/extended use. I hope you see the same!

The only ways I can see are:

1. color change (essentially a pH indicating dye)
2. pH (you'd need special fittings for in line pH measurement),
3. watching the TDS very closely. The TDs will drop back to match the incoming water to it when the first single bed is depleted.

 

[KJoFan]

The only ways I can see are:

1. color change (essentially a pH indicating dye)
2. pH (you'd need special fittings for in line pH measurement),
3. watching the TDS very closely. The TDs will drop back to match the incoming water to it when the first single bed is depleted.

Maybe it will turn out to be easier than I think in the end to tell. Based on what I'm seeing initially it would seem cation and mixed bed will last quite a bit longer than anion. Initially I'm seeing TDS readings that were something like 6-0-0, so based on that, when that second reading starts creeping up toward the first one I should be considering replacing. In theory the mixed bed will 'catch' those impurities but I don't want it to do the heavy lifting long term in order to keep product water good.

 

[tpack17]

I am running 2-anion then 2-cation on a well. This setup has saved me di over the mixes bed by far. I get about 200g per anion cartridge. I have not change the cation yet. So probably 2000g and cation is only quarter used up in first cartridge. Definitely worth it. And yes tds rises after first anion. I have tds meter before and after each cartridge.

 

[KJoFan]

The package said anion when depleted turns the yellow/gold color as seen in my pic. I wonder what that red splotch means. ;Hilarious