RODI - going through Anion resin like candy

jepuskar · Sep 17, 2023

Like the title says...I am going through Anion resin like it's candy. New tank filled with RODI water and I had the change the resin twice already. The Cation and Mixed Bed have yet to change colors even a little bit. The Anion changes colors almost immediately. It's soo bad I may have to change the resin one or every two water changes.

Below is my water quality and I also found a table on Aqua FXs website that lists what Anion resin handles. Based on that I'm guessing it's the sulfate...and yes, I know my TDS is awful. Perhaps I should buy stock in a DI resin company?

littlebeard · Sep 17, 2023

What is the tds after the ro membrane?

Buckeye Hydro · Sep 17, 2023

Are you feeding the RODI softened water?

jepuskar · Sep 17, 2023

The TDS right after the membrane is 11. I am using a 800ml flow restrictor and the pressure at the membrane is 80psi.

Yes, I am feeding it softened water. That is either a good thing or I'm going to be sweating pipe this morning.

Buckeye Hydro · Sep 17, 2023

feeding softened water to the RO is a good thing... and probably a mandatory thing in your case.

KStatefan · Sep 17, 2023

Is it possible that your water is high in CO2?

jepuskar · Sep 17, 2023

KStatefan said:
Is it possible that your water is high in CO2?

That water analysis I had done showed the pH at 7.85, so I'm guessing no otherwise that value would be much lower...right?

Buckeye Hydro · Sep 17, 2023

I calculate 10 ppm co2 based on your pH and Alk.

I don't have any faith in your pH number - that really has to be measured onsite.

jepuskar · Sep 20, 2023

Measured pH pre RO unit and got 6.88.

Based on all the other kids having the same issues...looks like I'm going to be aerating water pre DI stage.

KStatefan · Sep 21, 2023

I never could get gravity flow thru my di to work consistently so switched to pumping thru the di stages.

jepuskar · Sep 23, 2023

KStatefan said:
I never could get gravity flow thru my di to work consistently so switched to pumping thru the di stages.

So what do you use to pump water through the DI stage? A doser or a low gph normal pump and at what flow rate? If you have a link or something that would be cool.

This looks like what I will go with:

Pump water through RODI system without faucet

I have burned through both my Di resin canisters after about 60 gallons of production from my BRS 6 stage 150gpd. Tds in to di is 5 and tds out is still 0. I’ve learned that the well water I’m using is likely high in CO2 so I will have to “degass” the water. I think building a degassing tower is...

www.reef2reef.com

KStatefan · Sep 24, 2023

jepuskar said:
So what do you use to pump water through the DI stage? A doser or a low gph normal pump and at what flow rate? If you have a link or something that would be cool.

This looks like what I will go with:

Pump water through RODI system without faucet

I have burned through both my Di resin canisters after about 60 gallons of production from my BRS 6 stage 150gpd. Tds in to di is 5 and tds out is still 0. I’ve learned that the well water I’m using is likely high in CO2 so I will have to “degass” the water. I think building a degassing tower is...

www.reef2reef.com

I use a Tunze ATO pump. I think in the future I will switch it to an Aquatec 5800

Buckeye Hydro · Sep 24, 2023

KStatefan said:
I use a Tunze ATO pump. I think in the future I will switch it to an Aquatec 5800

Be aware those pumps are available in various GPM capacities and with various power requirements 12v, 24 v, 110v, AC/DC

KStatefan · Sep 24, 2023

Buckeye Hydro said:
Be aware those pumps are available in various GPM capacities and with various power requirements 12v, 24 v, 110v, AC/DC

Yes. That is why I selected the one I pictured.

Randy Holmes-Farley · Sep 26, 2023

I'll just make a few comments for future readers of this thread, and I concur that CO2 is the issue.

1. The incoming water and the effluent after the RO membrane but before the DI MUST be charged balanced. That is, total anion charge = total cation charge.

2. Due to 1, anion and cation resins will be depleted equally UNLESS there is an ion present in large quantity that does not deplete the resins. The only two ions that do not deplete the resins are H+ and OH-.

3. Thus, we have to lay the blame for uneven depletion on either HCO3- (bicarbonate) where it comes apart to H+ and CO3-- and thus depletes the anion resion but not the cation resin, or H2PO4/HPO4-- and Si(OH)4, both of which do the same thing.

4. From the water report, we see a huge amount (480 ppm) of alkalinity (bicarbonate at that pH) which also gets through the RO pretty well as carbonic acid. SIlicate/silica, while significant, is far lower, and phosphate, while also possibly significant (its not shown) cannot possibly be that high. Thus, bicarbonate/CO2 is the cause of the rapid depletion of the anion resin.

jepuskar · Sep 26, 2023

If I lived about 1 mile North I would be on Lake Michigan water and not have this issue...but ohh well. Fortunately my fish room is adjacent to the garage, just in the basement with an easy way in. I get to route my skimmer air intake from the garage(about 1000ppm) less CO2 and now I get to aerate my RO water in a brute in the garage. What a conversation piece.

Derrick0580 · Sep 26, 2023

I stopped going through so much anion after I added the water saver membrane and pump from bulk reef….up until then I got around 150 gallons per cartridge refill, now I’m around double that.

Buckeye Hydro · Sep 27, 2023

Derrick0580 said:
I stopped going through so much anion after I added the water saver membrane and pump from bulk reef….up until then I got around 150 gallons per cartridge refill, now I’m around double that.

plumbing membranes in series doesn't affect CO2. If you have hard water or high TDS, plumbing membranes in series will increase the TDS of your permeate.

Debramb · Sep 27, 2023

We finally have 0 TDS on our softened well water! Our Phosphates were through the roof, algae on live rock. Trying to stabilize current tank before our upgrade! We have 5 stage R/O DI from BRS

jepuskar · Oct 12, 2023

Just wanted to say thank you for the help here. I'm diverting my RO water out to my garage, have a couple bubblers going and about 24 hours later I have a PH around 8.x. I am then using an Aquatic 5800 pump to send it through my DI and then into my storage container.

The Anion resin canister has actually reverted color a little away from the brown that was creeping up.

Thanks again.