RO DI Resin Filters?

WVReefJunkie · Jan 23, 2023

I have been using Spectapure ten inch mix bed DI filters, and having issues with fast depletion. I have a couple of questions here, first is there any added benefits in the resin, between a pre packaged and refilliable? Second I am burning through two Spectapure filters after 200 gallons of 0 tds water, does my RO membrane need replaced?

I took some readings earlier, here are my specs

5 stage system
Tds after Ro Membrane 44
After Di Filters 0
Water temp after Ro 74.1
Water Pressure on system 42psi
75 GPD Membrane
I have never changed the flow restrictor in the system, and is estimated 10 years of age.

JDCagley · Jan 23, 2023

Your post membrane number seems really hight to me. Mine is 3-5 into the resin. No wonder you're burning through resin. I only get about ~300 gallons before I start seeing 1 TDS. Swap #2 into #1 slot, and add new to end of line.
Edit - my water is really hard here also. Pre unit is near 200TDS, sometimes a little higher.

EeyoreIsMySpiritAnimal · Jan 25, 2023

WVReefJunkie said:
I have been using Spectapure ten inch mix bed DI filters, and having issues with fast depletion. I have a couple of questions here, first is there any added benefits in the resin, between a pre packaged and refilliable? Second I am burning through two Spectapure filters after 200 gallons of 0 tds water, does my RO membrane need replaced?

I took some readings earlier, here are my specs

5 stage system
Tds after Ro Membrane 44
After Di Filters 0
Water temp after Ro 74.1
Water Pressure on system 42psi
75 GPD Membrane
I have never changed the flow restrictor in the system, and is estimated 10 years of age.

What is your TDS put of the tap?
What kind of carbon filters do you use? If your tap water has chloramines, your di resin might be absorbing ammonia.

Your water pressure is pretty low. Most membranes are tested at 50 psi (which just means that the rejection rate is calculated at that pressure, not that it won't work at all at lower psi... but adding a booster pump may help)

WVReefJunkie · Jan 25, 2023

Erin1971Texas said:
What is your TDS put of the tap?
What kind of carbon filters do you use? If your tap water has chloramines, your di resin might be absorbing ammonia.

Your water pressure is pretty low. Most membranes are tested at 50 psi (which just means that the rejection rate is calculated at that pressure, not that it won't work at all at lower psi... but adding a booster pump may help)

My tap water is 184 TDS

gbroadbridge · Jan 25, 2023

WVReefJunkie said:
My tap water is 184 TDS

Something is wrong with either the membrane or the plumbing configuration.

With 184ppm in you should be seeing under 9 ppm after the membrane - probably closer to 5 ppm.

Derrick0580 · Jan 25, 2023

I was having the same issue until I added a brs water saver system and a booster pump. Now I’m at around 200 gallons made and see a very small area in the anion(i run separate cat/an ion resins) that is starting to change color.

KStatefan · Jan 25, 2023

WVReefJunkie said:
My tap water is 184 TDS

As was posted above you should be around 5 tds after the membrane. How old is the membrane and carbon filters?

Troylee · Jan 25, 2023

Having the same problem… my psi is only 42 and my tds going in is 512 YIKES! Vegas water is nasty haha! I’m getting 14 out of the membrane and burning di resin up quick.. I’m gonna try a booster pump and raise the psi and see what happens.. waiting on a pressure switch I already had a pump.

nuxx · Jan 25, 2023

Bought knock off resin from eBay and lasted a decent amount of time on my 650 total gallon system.

Was also doing 5 gallon water changes every day and ATO.

EeyoreIsMySpiritAnimal · Jan 25, 2023

Troylee said:
Having the same problem… my psi is only 42 and my tds going in is 512 YIKES! Vegas water is nasty haha! I’m getting 14 out of the membrane and burning di resin up quick.. I’m gonna try a booster pump and raise the psi and see what happens.. waiting on a pressure switch I already had a pump.

That's a pretty good reduction, over 97% rejection rate. Booster pump can help you produce water more quickly, but I'd change/ add to your pre-membrane filtration. Something is making it through the membrane that's reacting with your resin... Better/more carbon blocks may help.

Troylee · Jan 25, 2023

Erin1971Texas said:
That's a pretty good reduction, over 97% rejection rate. Booster pump can help you produce water more quickly, but I'd change/ add to your pre-membrane filtration. Something is making it through the membrane that's reacting with your resin... Better/more carbon blocks may help.

I got a six stage unit.. pre filter then carbon block, chlora gaurd carbon block, membrane and dual di resin beds.. my automatic shut off isn’t working either after my tank is full and float shuts it off… the unit will continue to produce waste water till I close the faucet off. I’m guessing the psi isn’t enough on the bladder but I’ll soon find out! I’ve tried changing flown restrictors, check valves etc..

chipmunkofdoom2 · Jan 25, 2023

Troylee said:
Having the same problem… my psi is only 42 and my tds going in is 512 YIKES! Vegas water is nasty haha! I’m getting 14 out of the membrane and burning di resin up quick.. I’m gonna try a booster pump and raise the psi and see what happens.. waiting on a pressure switch I already had a pump.

Your pressure could be a little better, but even still, your water post-membrane is about as good as you can hope for. You might be able to knock 5 ppm or so off. But you're probably not going to get 2 or 3 TDS out of your membrane.

Troylee · Jan 25, 2023

chipmunkofdoom2 said:
Your pressure could be a little better, but even still, your water post-membrane is about as good as you can hope for. You might be able to knock 5 ppm or so off. But you're probably not going to get 2 or 3 TDS out of your membrane.

Yeah I figured that much… the pumps worth a shot since I already had it.. just had to buy a pressure switch which comes tomorrow.. see what happens.

chipmunkofdoom2 · Jan 25, 2023

WVReefJunkie said:
I have been using Spectapure ten inch mix bed DI filters, and having issues with fast depletion. I have a couple of questions here, first is there any added benefits in the resin, between a pre packaged and refilliable? Second I am burning through two Spectapure filters after 200 gallons of 0 tds water, does my RO membrane need replaced?

I took some readings earlier, here are my specs

5 stage system
Tds after Ro Membrane 44
After Di Filters 0
Water temp after Ro 74.1
Water Pressure on system 42psi
75 GPD Membrane
I have never changed the flow restrictor in the system, and is estimated 10 years of age.

A quality 75GPD membranes should reject at least 95% of TDS. So worst case, your TDS should be around 10 post membrane. That alone will go a long way to making DI resin last longer.

Ultimately, it sounds like you need to replace the membrane, but I'd start by replacing all your prefilters first. The prefilters protect the membrane, so there's not much sense replacing the membrane if your prefilters are shot. Get a small (1 micron) sediment filter, and get quality carbon blocks. Then, replace your membrane. If TDS doesn't improve, try checking your recovery rate (how much RO is made vs how much "waste water" is produced). Some systems try to "conserve" water by choking the membrane with ridiculously high recovery rates. This kills the membranes prematurely and produces crap water quality. Ideal ratios per Dow's documentation is about 1:4, or 1 gallon of fresh water for every 4 gallons of waste water.

If that doesn't get the TDS down, you'll probably need to add a booster pump. Be sure to re-check recover rates after changing or modifying your restrictor, as the ratio will change at different pressures.

Troylee · Jan 25, 2023

chipmunkofdoom2 said:
Your pressure could be a little better, but even still, your water post-membrane is about as good as you can hope for. You might be able to knock 5 ppm or so off. But you're probably not going to get 2 or 3 TDS out of your membrane.

I have a second membrane I was thinking about running.. not sure if that would help or not.. def need a booster pump then lol..

chipmunkofdoom2 · Jan 25, 2023

Troylee said:
I have a second membrane I was thinking about running.. not sure if that would help or not.. def need a booster pump then lol..

I wouldn't personally. I don't believe second membranes in series help. But plenty of people do it this way.

Graemesreef · Jan 25, 2023

Not to hijack but sense were on the topic, any ideas on whats burning up my di with city water at 28 and 0 out of the membrane? Never happened before the last 2 replacements, chance of a bad batch of resin?

PatW · Jan 25, 2023

I have an RO membrane from Bulk Reef Supply. I think it is a GE product. My water is about 120-150 tds. It comes out of the RO at 2 and after awhile 1. I do preflush the membrane.

I pack my own DI canisters. I get the color changing Resin from BRS. I get about 300 gallons per DI canister. Packing the canister takes a bit of a knack but once you get it down, you can do your own just as well as store packed and cheaper too.

WVReefJunkie · Jan 25, 2023

nuxx said:
Bought knock off resin from eBay and lasted a decent amount of time on my 650 total gallon system.

Was also doing 5 gallon water changes every day and ATO.

You have link?