My tap dkh is 11.6 - Will R/O remove this?

[CherBear811]

Hey all! So in a pinch made a batch of sw for a wc using tap, and tested alk with hanna checker just to see what it was (using LA salt, which has 9 dkh). Hanna checker blinked 300, so I retested and got the same result. That's about 15.6 dkh but since it was blinking, I decided to check plain tap. It was 11.5 dkh. Needless to say, I did not use that batch of water.

I was just going to get an r/o buddy, but now I am wondering what all I need to reduce dkh that is that high? City website says the city TDS is about 700.

Thinking of shifting gears to a BRS unit... But do I need a second membrane canister, or carbon or D/I?

Thanks!

 

[roberthu526]

WOW 700! You will need something serious with a dual DI cartridge I think. And DI is probably a must.

 

[chinw76]

DI will change Ph between resins. DKH would be hardness of the water. I don't know how much the ro will pull out. A water softner for the house would lower this as it makes the water soft.

 

[CherBear811]

@Randy Holmes-Farley Can you offer any insight on dealing with high dkh in house tap? Will r/o reduce that and if so, which part of the unit?

* I know I will need dual D/I to deal with the 700 TDS, but at this point I am more concerned with dkh.

 

[chinw76]

My warer is ar 360pmm, even with dual di resins, I would do a water change and I would have issues with stuff growing on my sand. I now run 6 di resin beds, 2 brs pro cation resins, 2 pro anion resin, then 2 mix beds. Since then, no more problems with water changes. I automated it to flush the membrane and dump water for 4 mins before it goes into my di.

 

[CherBear811]

My warer is ar 360pmm, even with dual di resins, I would do a water change and I would have issues with stuff growing on my sand. I now run 6 di resin beds, 2 brs pro cation resins, 2 pro anion resin, then 2 mix beds. Since then, no more problems with water changes. I automated it to flush the membrane and dump water for 4 mins before it goes into my di.

Holy water production, Batman!! ;Wideyed Do you have to use a pressure booster to get your water through all of that??

 

[Crabs McJones]

My warer is ar 360pmm, even with dual di resins, I would do a water change and I would have issues with stuff growing on my sand. I now run 6 di resin beds, 2 brs pro cation resins, 2 pro anion resin, then 2 mix beds. Since then, no more problems with water changes. I automated it to flush the membrane and dump water for 4 mins before it goes into my di.

WOW that is quite the setup!

 

[CherBear811]

So I talked to BRS. The guy had to ask his supervisor questions a couple of times, but basically, he recommended....

1-Sediment cartridge
1-R/O membrane cartridge
1-2 Carbon cartridges
1-Cation cartridge
1-Anion cartridge
1-Mixed bed resin cartridge

He said to pay attention to which resin exhausts first and consider adding a second cartridge of that before the mix bed polishing cartridge. So, 6-7 cartridge set up should do it. Thankfully I do not have a huge tank (and I wont get one until I am in a home owning situation). Lol

Anyone else have experience with high TDS?

 

[themcfreak]

My warer is ar 360pmm, even with dual di resins, I would do a water change and I would have issues with stuff growing on my sand. I now run 6 di resin beds, 2 brs pro cation resins, 2 pro anion resin, then 2 mix beds. Since then, no more problems with water changes. I automated it to flush the membrane and dump water for 4 mins before it goes into my di.

WOWSERS! What is the TDS before it hits your system?

Also, I don't see (and didn't see in your type), do you not run a R/O membrane? Wouldn't that help lower the TDS before it gets to the DI resins, in theory reducing the amount of DI you need?

 

[pickupman66]

wow you guys must have rocks coming out of your faucets. talk about crappy water...

themcfreak, yes, I see a membrane on the top laying down in his system.

 

[themcfreak]

wow you guys must have rocks coming out of your faucets. talk about crappy water...

themcfreak, yes, I see a membrane on the top laying down in his system.

oh yes, i see that now. The canister tool in front of it threw me off.

 

[Potatohead]

Something nobody pays attention to it seems is pressure. With that much TDS you will save yourself a LOT of money by using a booster pump and getting as much pressure through the membrane that you can (80-90 psi, maybe more). If you can halve the amount of TDS coming out of the membrane simply by using pressure you will double the life of your DI.

If it was me I would run it in this order:

5 micron sediment
1 micron sediment
1 micron carbon (dual stage likely necessary if your area uses chloramine)
booster pump
membrane
dual DI stages (regular mixed stuff)

 

[themcfreak]

Something nobody pays attention to it seems is pressure. With that much TDS you will save yourself a LOT of money by using a booster pump and getting as much pressure through the membrane that you can (80-90 psi, maybe more). If you can halve the amount of TDS coming out of the membrane simply by using pressure you will double the life of your DI.

If it was me I would run it in this order:

5 micron sediment
1 micron sediment
1 micron carbon (dual stage likely necessary if your area uses chloramine)
booster pump
membrane
dual DI stages (regular mixed stuff)

But a typical 75GPD RO membrane (from BRS, at least) is rated at 50 PSI to get 99% rejection. I honestly don't know, but would increasing pressure to 80-90 mess with the 99% rejection rate? I see that maximum is 150psi, but what effect does higher than rated PSI have?

 

[BZOFIQ]

My warer is ar 360pmm, even with dual di resins,

Wait what; that really doesn't make sense. What is your TDS after the membrane???

 

[CherBear811]

Something nobody pays attention to it seems is pressure. With that much TDS you will save yourself a LOT of money by using a booster pump and getting as much pressure through the membrane that you can (80-90 psi, maybe more). If you can halve the amount of TDS coming out of the membrane simply by using pressure you will double the life of your DI.

If it was me I would run it in this order:

5 micron sediment
1 micron sediment
1 micron carbon (dual stage likely necessary if your area uses chloramine)
booster pump
membrane
dual DI stages (regular mixed stuff)

I asked about running 2 sediment filters, and the guy said he felt it would really reduce pressure. But we were talking about the 1 micron sediment filter so maybe a 5 micron prefilter might be a good idea. My city doesn't use chloramine and actually has pretty low chlorine (I've tested that myself). I attribute this to being a heavy ag area where a lot of farmer have to rely on irrigation and heavy chlorine/chloramine would be bad for crops.

I asked if I only needed 1 carbon block since we don't have chloramine and relatively low chlorine, and he said he would still run the dual.

I've thought about the booster pump. Think I will get a pressure gauge and see where I am at going in to the DI cartridge. I didn't know you could use a booster pump in the middle of the unit though. Is that common? Excuse my ignorance on this topic. A good ole 4 stage was more than good enough where I lived before moving here. Lol

 

[CherBear811]

The guys at BRS estimated that starting at 700 TDS, with a sediment, dual carbon and membrane, my tds at that point should be about 35, and that the DI would clear out the rest. Does that sound inline with people's experience?

 

[Potatohead]

But a typical 75GPD RO membrane (from BRS, at least) is rated at 50 PSI to get 99% rejection. I honestly don't know, but would increasing pressure to 80-90 mess with the 99% rejection rate? I see that maximum is 150psi, but what effect does higher than rated PSI have?

In the OP's case if he increases rejection from 99% (700 tap down to 7) to 99.5% (3.5 ppm) you double your resin life. Unless you don't make much water this will pay for the cost of a booster pump in quite a short time.

I asked about running 2 sediment filters, and the guy said he felt it would really reduce pressure. But we were talking about the 1 micron sediment filter so maybe a 5 micron prefilter might be a good idea. My city doesn't use chloramine and actually has pretty low chlorine (I've tested that myself). I attribute this to being a heavy ag area where a lot of farmer have to rely on irrigation and heavy chlorine/chloramine would be bad for crops.

I asked if I only needed 1 carbon block since we don't have chloramine and relatively low chlorine, and he said he would still run the dual.

I've thought about the booster pump. Think I will get a pressure gauge and see where I am at going in to the DI cartridge. I didn't know you could use a booster pump in the middle of the unit though. Is that common? Excuse my ignorance on this topic. A good ole 4 stage was more than good enough where I lived before moving here. Lol

I don't know who you talked to but his advice is like the opposite of what I would do, lol. Pressure reduction won't be that bad, maybe 3-5 psi tops. Since you don't have chloramines I would do five micron sediment, one micron sediment, one micron carbon.

Yes it is common to run out of your carbon into the pump and back into the membrane, just make sure the pre-filters are getting at least about 40 psi and you meet the minimum inlet pressure on the pump. The reason to do it this way is to a) protect the pump from sediment and b) avoid all that extra pressure on the pre-filter canisters.

The guys at BRS estimated that starting at 700 TDS, with a sediment, dual carbon and membrane, my tds at that point should be about 35, and that the DI would clear out the rest. Does that sound inline with people's experience?

35 out of the membrane is not very good (95% rejection) and will use tons of DI really fast. With a good membrane you should easily see 98-99% rejection, especially with lots of pressure.

 

[CherBear811]

35 out of the membrane is not very good (95% rejection) and will use tons of DI really fast. With a good membrane you should easily see 98-99% rejection, especially with lots of pressure.

Well normally I would agree, but he was referring to a starting TDS of 700. I asked about running 2 membranes, and he said it would tank efficiency, that after the second membrane I would be looking at about 10 gallons of waste water to every 1 gallon produced. I can't in good conscience do that, way too wasteful. So, that leaves letting DI do the rest of the work. Unless you see another way? I mean, the 5 micron sediment before the 1 micron wouldn't really change the 35, it would just keep the 1 micron from clogging as fast, right?

 

[CherBear811]

Just checked the website again (last time I looked was last year).... Says TDS is 575 mg/L. That's not much better, but it is better. Someone must have noticed we were over federal standards, which is 500. Still not under but it's better... still seems like a big number to reduce to 0.

 

[Potatohead]

Well normally I would agree, but he was referring to a starting TDS of 700. I asked about running 2 membranes, and he said it would tank efficiency, that after the second membrane I would be looking at about 10 gallons of waste water to every 1 gallon produced. I can't in good conscience do that, way too wasteful. So, that leaves letting DI do the rest of the work. Unless you see another way? I mean, the 5 micron sediment before the 1 micron wouldn't really change the 35, it would just keep the 1 micron from clogging as fast, right?

Don't need two membranes. Starting TDS is kind of irrelevant. Your output from DI will (should) always be zero, the only real difference is how often you are changing out your DI resin. A decent membrane will reject 98-99% at higher pressure without a problem. You can put 100 TDS into the DI and it will (should) come out zero, but it will deplete quickly. You can spend ~$20 a month (or whatever) on DI or you can buy a $90 pump that will last years and spend $10 a month on DI and have to do less maintenance with it. Seems a no brainer to me.

The filters before the membrane don't remove any TDS, they are simply protecting the membrane from debris and chlorine.