Help with ro/di filter replacement please

[justingraham]

I control my ro unit with my apex so I am able to see how long it runs.

I ran my unit for 6 months and found that my ro ran 2460 minutes in that time.

I found out that for every 150 mins it runs my ro unit produces 25 gallons of good water. (It’s a 35 gallon brute can that I make sure I always have ten gallons on hand so the solenoid kicks on roughly with ten gallons left in it and shuts off at the brim automatically which is so easy)

So if my ro unit ran for 2460 minutes and we know that 150 mins equals 25 good gallons that means that (by my math anyway) I made 410 zero tds water.

I do not know my rejection rate but I do run it with a booster pump(the ro buddie) at 85-90 psi if memory serves me correct.

So if we say it is for every one gallon of zero tds water i waste three that means 1230 gallons went thru my unit in six months. I run a hybrid 6 or 7 stage (I don’t know) of one sediment two carbons two di’s And two membranes.

When I changed my filters I just did it because it was at the six month mark and I was going on vacation. It was still producing 0 tds.

So do you think I change my filters out too soon?

I guess it would help if u know what filters I replaced.
Brand new sediment filter.
Moved my 2nd carbon filter to my first slot and put a new carbon in second slot.
Moved my second di to my first slot and put in a new di in second slot.

I forgot to record the tds before and after every filter as I have a three and a two inline tds meter I will do that next time if I remember. But my tds going in is 144

Hope that’s enough info

And a picture because everyone loves pictures

This is before I added the second membrane

and before I cleaned up the wires for my trash can

 

[Opus]

Changing your pre-filters (carbon and sediment filters) is different from your DI. In theory you should change your pre-filters when they become clogged. This usually isn't practical for most people so the rule of thumb is to usually do it every 6 months to a year. Their only purpose is to protect the RO membrane from debris and chemicals. The DI should be changed once you see the tds go above 0. Then you would move the second DI to the first position and refill the first cartridge and put it in the second position.

You don't mention your tds after the RO membrane but before the DI so I will guess on this part. You say your initial tds is 144 so if you are getting a 98% rejection rate you are looking at around 3 tds before the DI. This means you should get around 1500 gallons of 0 tds water out of your first DI filter assuming no CO2 issues. If you are getting 99% rejection rate, then you are looking at around 3000 gallons of 0 tds from your first DI.

 

[justingraham]

Changing your pre-filters (carbon and sediment filters) is different from your DI. In theory you should change your pre-filters when they become clogged. This usually isn't practical for most people so the rule of thumb is to usually do it every 6 months to a year. Their only purpose is to protect the RO membrane from debris and chemicals. The DI should be changed once you see the tds go above 0. Then you would move the second DI to the first position and refill the first cartridge and put it in the second position.

You don't mention your tds after the RO membrane but before the DI so I will guess on this part. You say your initial tds is 144 so if you are getting a 98% rejection rate you are looking at around 3 tds before the DI. This means you should get around 1500 gallons of 0 tds water out of your first DI filter assuming no CO2 issues. If you are getting 99% rejection rate, then you are looking at around 3000 gallons of 0 tds from your first DI.

Yea I’m in Texas right now so when I get home I will get those tds numbers for you I want to say it was between 3-5???

Not to sure tho

So ur saying I should change filters and di at different times?
I’m a lazy forgetful person

 

[Opus]

Yea I’m in Texas right now so when I get home I will get those tds numbers for you I want to say it was between 3-5???

Not to sure tho

So ur saying I should change filters and di at different times?
I’m a lazy forgetful person

You can change them at the same time but you are probably wasting money since the DI is still good. Now is that $5 to $10 wasted worth it to you to not change at the same time, that is up to you. I'm a very lazy person so I usually let my tds got to 4 or 5 before I change the DI.

You didn't mention it, but I assume you know the RO membranes should last several years with some people on here going to 8+ years on the same RO membrane.

You have good water for Texas. Mine is usually between 400 and 450 tds at the faucet.

 

[justingraham]

O I’m in Texas I live in New Jersey

And the last time my tds was at one my Corals were stn’ing so whatever that one was was harmful

And that’s my plan to keep my membranes for seven years

That’s why I want to know the best easiest way to make sure that happens and I’m not worried about 5-10 dollars in this hobby if it means my pets are okay

I just know myself if I set one up for six months and the other for 8 I’ll forget

And thank you for the response

Justin

 

[chipmunkofdoom2]

The only thing that final TDS will tell you is if your DI resin is depleted. It will not tell you anything about any of your other filters. You need to test for those specifically or replace them on a schedule.

For the prefilters (sediment filter, carbon blocks), you can replace them on a six month schedule if you don't feel like monitoring them and testing them. If you want to be more intelligent about the replacement, you can do so by testing.

For the sediment filter, monitor the pressure before and after the prefilters. Once the pressure begins to drop significantly, you need to replace the sediment filter. If the pressure does not increase after replacing the sediment filter, it's likely the case that the sediment filter was too big and the carbon blocks are plugged. You'll need to replace those too.

The carbon blocks need to be replaced once they start letting chloramine/chlorine through. Test the waste water with chlorine/chloramine test strips. If any chlorine/chloramine is detected, the carbon blocks need to be replaced as soon as possible. Chlorine in particular is pretty hard on TFC membranes.

For the RO membrane, you'll only need to replace this every few years (my last membrane lasted 10 years). To determine if the RO membrane needs to be replaced, test the rejection rate. Test the TDS of your tap water, then test the TDS after the membrane but BEFORE the DI stage. Divide the second number by the first. The rejection rates for most Dow membranes should be > 96%. That means the number you get here should be 0.04 or less. If it's any higher than 0.04, you may want to consider replacing the membrane.

The DI resin, as discussed, is the only one you can tell needs to be replaced by final TDS. If the TDS is above zero or if the color change indicates the resin is depleted, it's time to replace it.

 

[Zack@BRS]

@justingraham Some great answers above. I would pretty much mirror what chipmunkofdoom said. The BRS Universal 1 micron carbon blocks are rated for up to 3,500 gallons of chloramine treated water or 35,000 gallons of chlorine treated water. Chlorine/chloramine concentrations can vary, so these numbers are approximate. If you're changing out filters after ~ 1,230 gallons of water through the blocks, then you may very well be replacing them sooner than needed, but the surest way to know is to test with a chlorine test like the strips.

Bacterial fouling can also be an issue for some people, so between that and the fact that many people just like to change filters out regularly for peace of mind and scheduling, we often recommend replacing all pre-filters every six months or so. I would treat DI resin differently as that can be much more variable based on your tap water TDS and water production needs. Use the color change to keep tabs on things, especially when you're getting to around 90% color change. If you run two DI stages, I'd personally replace the first one before it completely changes color to avoid dumping a bunch of stuff into the 2nd cartridge when it exhausts.

 

[Heavysledz]

I found out that for every 150 mins it runs my ro unit produces 25 gallons of good water.

Not that I don't believe you but am curious how you are making 10 gallons of RO/DI an hour with only a single RO membrane setup. Are you running a booster pump and if so what pressure? I have the BRS 6 stage that was producing 2.5 gallons/hr @58 PSI incoming water pressure (@50' F). I added a second RO membrane in series and still only get about 5.2 gallons/hr. So am very curious how you are getting 4X what I am with only a single RO membrane setup.

 

[justingraham]

Not that I don't believe you but am curious how you are making 10 gallons of RO/DI an hour with only a single RO membrane setup. Are you running a booster pump and if so what pressure? I have the BRS 6 stage that was producing 2.5 gallons/hr @58 PSI incoming water pressure (@50' F). I added a second RO membrane in series and still only get about 5.2 gallons/hr. So am very curious how you are getting 4X what I am with only a single RO membrane setup.

Have the booster buddy with 80-90 psi I don’t know what my temp is
I have since added a second membrane and just recently made 50 gallons of water in four hours and 35 mins