Rodi filters depleting too fast

[Oshanickreef]

Hello,

I am having issues with my 7-stage dual membrane 150GPD RODI unit. First off, I’m running off of a well and my unit is hooked up after my water softener. My DI resins are in order starting with cation, then anion, then mixed bed. After setup I made maybe 15 gallons of water and the second DI canister (anion resin) is almost 1/4 color changed. I just can’t believe that will be my normal rate of exhaustion on any of the DI canisters. TDS going into the membranes is 440 and coming out of the membranes is 12. TDS going into the first two di canisters is 12-10 and zero after that. Booster pump has my pressure at 80psi.
Anybody have any ideas what’s going on? I’m stumped over here.
Thanks,
Nick

 

[twentyleagues]

I just set up the same system, on a well, with a booster pump. My anion is already turning also but just a little. I made around 60g so far. Anion removes silicate. I'm guessing you have a high level higher then mine. I don't know what my silicate lvl is. I will be investing in a new home softener and whatever else I need in the next couple of months. They will test the water first. I was just going to send in a test myself and install it myself but I am tired of looking up filter info. The softener Ive got now was here when I moved in. It does little to nothing for the liquid rock I have. I also have iron in abundance my tub and toilets are orange in a week. I'm not sure what else specifically the anion resin removes I was googling it a couple nights ago, because I noticed it starting to change already. Apparently ro membranes don't remove silicate.

 

[Oshanickreef]

I was wondering about silica. Apparently you can use a mix of mixed bed di resin and a little bit of either cation or anion resin and that acts as a silica removal cartridge.

I picked up a silica test kit by seachem on Amazon so I’ll be testing to see what’s going on. Would love to figure this out. Stressing me out how fast I have been burning through Di. My system I am setting up is going to be around 450 gallons and that would cost like 500 dollars in di to fill up my tank….

 

[twentyleagues]

Yeah I hear you I've got a 300+g system I'm working on too. Post up your findings. When I upgrade my house and get testing done I'll post also.

 

[Gtinnel]

I am not on well water so my knowledge on this issue is simply from what I’ve heard others discuss. I know of a few reefers on well water who have to let their well water sit and off gas to remove some of the co2 because the co2 will quickly deplete their di.
I don’t know if this is your issue but it may give you a idea to try to research.

I will see if I can find a thread I remember where it was talked about.

 

[edd59]

i have the same unit on well water. most well water has high co2. i get about 1-200 gal out of anion but the others are fine. the reason for 3 differant resins.
check your ph out of tap then let it sit 24 hrs and ck again. if you have high co2 you will have low ph from tap and will rise after sitting

 

[Randy Holmes-Farley]

I agree that CO2 in well water can be a DI killer.

 

[twentyleagues]

Previously to this ro unit to test if the ph would rise in my well water was futile. My ph out of tap is 9.4 and gh and kh are both around 15. I tried it and ph didn't change. I made a black water tank using peat and a ton of botanicals and new spider wood that leaches tannins a lot. I couldn't get the ph below 8.5 and the kh/gh were still 12. I could not see the back of a 18" wide tank. Now with the ro unit i will try again. Ill take a sample of water out of the ro unit before the di stage tds meter is around 15 at that stage. Ill get kh and gh too. If it is co2 then I can get another water holding container and off gas using a air pump then pump it some how through the di stages. Op could try same, i'll post findings.

 

[Randy Holmes-Farley]

Previously to this ro unit to test if the ph would rise in my well water was futile. My ph out of tap is 9.4 and gh and kh are both around 15. I tried it and ph didn't change. I made a black water tank using peat and a ton of botanicals and new spider wood that leaches tannins a lot. I couldn't get the ph below 8.5 and the kh/gh were still 12. I could not see the back of a 18" wide tank. Now with the ro unit i will try again. Ill take a sample of water out of the ro unit before the di stage tds meter is around 15 at that stage. Ill get kh and gh too. If it is co2 then I can get another water holding container and off gas using a air pump then pump it some how through the di stages. Op could try same, i'll post findings.

You cannot really judge by a pH drop or not, but a calculation based on pH (9.4) and alk (15 dKH) suggests CO2 is not the issue. The OP can do a similar test.

 

[twentyleagues]

You cannot really judge by a pH drop or not, but a calculation based on pH (9.4) and alk (15 dKH) suggests CO2 is not the issue. The OP can do a similar test.

Yeah thats what I was thinking. I figure that with the ro it may now be somewhat possible to see if there is bound co2 since the ph and kh/gh should be lower after the now. Honestly I haven't checked yet. All I know is tds is 0 on product water.

 

[Dburr1014]

Hello,

I am having issues with my 7-stage dual membrane 150GPD RODI unit. First off, I’m running off of a well and my unit is hooked up after my water softener. My DI resins are in order starting with cation, then anion, then mixed bed. After setup I made maybe 15 gallons of water and the second DI canister (anion resin) is almost 1/4 color changed. I just can’t believe that will be my normal rate of exhaustion on any of the DI canisters. TDS going into the membranes is 440 and coming out of the membranes is 12. TDS going into the first two di canisters is 12-10 and zero after that. Booster pump has my pressure at 80psi.
Anybody have any ideas what’s going on? I’m stumped over here.
Thanks,
Nick

High co2
I have the same problem with my well.
Mine is about 50tds in and about 2 TDS out and into the cation/anion/mixed bed.
After about (5) 30 gallon runs, anion is used up.

I use lye to regenerate the anion. Takes about 30ish minutes and run to the system to make sure it's all clear. (disconnect the mixed bed to clear)

 

[edd59]

can you explain the lye treatment please. never heard of it, i use a lot of anion. thanks

 

[Randy Holmes-Farley]

can you explain the lye treatment please. never heard of it, i use a lot of anion. thanks

Adding hydroxide converts most of the CO2 to carbonate or bicarbonate, which are more readily rejected by the RO membrane than CO2,a nd hence the DI lasts longer (though adding it when CO2 is not an issue will actualyl deplete it faster).

 

[Dburr1014]

There's this;

https://reefkeeping.com/issues/2008-09/nftt/index.php

But to do just anion;
Mix up the lye per the reefkeeping issue.
I lay a coffee filter in a plastic colander. Dip in the lye solution.
If you have the color changing type it will almost instantly change color. I wait a few minutes and take it out. Use rodi water to rinse. I do it over a 5 gallon bucket. It will take a gallon or two to rinse. I repack the resin into the container. Disconnect the mixed bed and start the rodi system. The TDS will be off the charts. Run until it's down to 1 or 2. Reconnect mixed bed and done.
You will lose some of the resin. It will stick to the filter or drop some, it's inevitable. It's good to have extra on hand for this.
I have recharged mine 5 or 6 times so far and it is still color changing. I have not touched my mixed bed in over a year, still reading 0 TDS.

 

[Randy Holmes-Farley]

There's this;

https://reefkeeping.com/issues/2008-09/nftt/index.php

But to do just anion;
Mix up the lye per the reefkeeping issue.
I lay a coffee filter in a plastic colander. Dip in the lye solution.
If you have the color changing type it will almost instantly change color. I wait a few minutes and take it out. Use rodi water to rinse. I do it over a 5 gallon bucket. It will take a gallon or two to rinse. I repack the resin into the container. Disconnect the mixed bed and start the rodi system. The TDS will be off the charts. Run until it's down to 1 or 2. Reconnect mixed bed and done.
You will lose some of the resin. It will stick to the filter or drop some, it's inevitable. It's good to have extra on hand for this.
I have recharged mine 5 or 6 times so far and it is still color changing. I have not touched my mixed bed in over a year, still reading 0 TDS.

OK, so you are talking about recharging the resin, not what I was thinking when i read the response, but i see that is what you intended.

 

[Oshanickreef]

OK, so you are talking about recharging the resin, not what I was thinking when i read the response, but i see that is what you intended.

Is there a way to lower co2 levels without recharging resin or letting the water gas off before going into the DI filters? I found a blog post about replacing the DI with a mix of 1/2 Seachem Phosguard and 1/2 polyfilter discs. I am nervous to try this but apparently these two medias are not affected by CO2 like the Di resin is.... I wonder if these two medias would work as a substitute for the DI? I don't have enough space to have multiple holding tanks so this seems like a neat option potentially. Would love to hear your thoughts on this, Randy.

thanks!

Nick