Confusion with replacing RODI canisters

[greetl01]

3-6 Months	650 Gallons of Filtered Water
3-6 Months	650 Gallons of Filtered Water

So I bought an RODI that was way too big for my tank. I only make about 10 gallons a week, and this is a 100/day max. My question is, do I replace after about 6 months no matter how much water i've filtered, or is it okay to keep the filters until I hit 650 gallons?

 

[mehaffydr]

I would keep the membrane until the TDS is no longer Zero. I would easily go a few thousand gallons before replacing other filters as long as TDS is ZERO. I would replace DI resin as needed. I use BRS color changing resin so its easy to know when to change.

 

[greetl01]

I would keep the membrane until the TDS is no longer Zero. I would easily go a few thousand gallons before replacing other filters as long as TDS is ZERO. I would replace DI resin as needed. I use BRS color changing resin so its easy to know when to change.

Thank you.

 

[zalick]

My process probably won't help you unless you install pressure gauges like my system. But here is what I do:
Replace sediment filter when pressure drops 10% across filter.
Replace carbon when it shows breakthrough chlorine.
Replace RO membrane when TDS removal is less than it's rating. Mine is 99% so I expect 0 TDs after running a few minutes
Replace DI when color change is full or anything but 0 TDS coming out.

I've processed well over 10,000 gallons on my current membranes.

 

[mdb_talon]

I have to assume the recommendations you listed were for prefilters not the ro membrane or even di. Even the most unscrupulous manufacturer would have a hard time suggesting ro replacement at 650 gallons or 6 months. Even with low usage i would personally replace my sediment/carbon filter at least yearly and likely mote frequently at reasonable usage. They dont last long and are very cheap(and help prolong life/improve efficiency of the more expensive components)

 

[TexanCanuck]

Agree with @mdb_talon ... replacing sediment & carbon pre-filters is important and a cheap way to keep your membrane in good shape.

Also agree that you should use your output water quality to judge when to replace membrane and DI cartridges ... using a calendar approach doesn't make sense to me.

However, I don't put a lot of faith in the color change resins ... just test the water after the resin and if it's not zero, then change the resin.

 

[pecan2phat]

When I use to perform regular water changes years ago, I would follow 6 months on the sediment and carbon cartridges to the tee and the resin only after TDS went above zero.
Now that I only will do 3 to 4 water changes annually, most of my water makeup is for top off and so I change the sediment and carbon annually. HTH

 

[Opus]

Zalick is doing it the correct way, but that way is a lot more inconvenient so manufacturers came up with the 3 to 6 month rule. The pre-filters only job is to protect the RO membrane. The sediment filter takes out the larger particles so the carbon and ro membranes do clog up prematurely. The carbon filters main job is taking out chlorine because chlorine (not chloramines) will destroy the ro membrane. The membrane then should take out at least 95% of everything else with the DI removing the rest. That is why you should never say your RO unit is working just because you are getting 0 tds from your unit. If we both have the same unit and my tap water is 400 tds and yours is 100 tds and we are both getting 8 tds water after the ro membrane, there is problem. I'm within spec because I'm running at 98% but you are not because you are at 92%. We would both be getting 0 tds water after our DI so if you were just doing an analysis based on that reading you would say both units are doing great.

You will see a gallon rating on a lot of the carbon blocks. This is based on a certain amount of chlorine in the water. You would need to know how much chlorine is in your water and do some algebra to come up with how many gallons that carbon block would last for you. I also don't go cheap on my pre-filters. My sediement filter cost about 2/3 of what my ro membrane cost but I wanted a very low micron rated filter.

 

[greetl01]

My process probably won't help you unless you install pressure gauges like my system. But here is what I do:
Replace sediment filter when pressure drops 10% across filter.
Replace carbon when it shows breakthrough chlorine.
Replace RO membrane when TDS removal is less than it's rating. Mine is 99% so I expect 0 TDs after running a few minutes
Replace DI when color change is full or anything but 0 TDS coming out.

I've processed well over 10,000 gallons on my current membranes.

How does one know when chlorine shows breakthrough? I’ve never heard that phrase or how to check it. Thank you. I’m going to go YouTube how to install gauged

*edit* for anyone else new to this stuff here’s a link how to install pressure gauges*

 

[KStatefan]

I use the Lamont Free-Total Chlorine test strips. Check my waste water to see if anything is there.

 

[Shirak]

Very important for anyone on treated municipal water to find out if they use chlorine and/or chloramine and how much. Then choose your carbon block based on that information. They have two ratings for how much chlorine and chloramine they can process in total gallons of water passed through the filter. Some can handle a lot of chlorine and very little chloramine. Some can handle both very well, hence the importance of knowing what is in your water. Then it is a simple matter of calculating how much total water you send through the filter to determine how long it can go before replacement. To do that collect both processed water and wastewater for a short period of time. Calculate how much total water it takes to get a gallon of RODI. So for example for example you send 5gal through the filter for 1gal of rodi and your carbon can process 10,000 gallon, you can get 2,000 gallons of rodi max from the carbon block. Probably best to replace a little before that though.

 

[Shirak]

Pool supply places will have a variety of chlorine testing stuff to monitor your waste water. Can also contact your local municipal water department and get a water report to find out what’s in your water

 

[zalick]

I use the Lamont Free-Total Chlorine test strips. Check my waste water to see if anything is there.

This is exactly what I do too. So easy

 

[zalick]

Very important for anyone on treated municipal water to find out if they use chlorine and/or chloramine and how much. Then choose your carbon block based on that information. They have two ratings for how much chlorine and chloramine they can process in total gallons of water passed through the filter. Some can handle a lot of chlorine and very little chloramine. Some can handle both very well, hence the importance of knowing what is in your water. Then it is a simple matter of calculating how much total water you send through the filter to determine how long it can go before replacement. To do that collect both processed water and wastewater for a short period of time. Calculate how much total water it takes to get a gallon of RODI. So for example for example you send 5gal through the filter for 1gal of rodi and your carbon can process 10,000 gallon, you can get 2,000 gallons of rodi max from the carbon block. Probably best to replace a little before that though.

Great advice.

My water has chloramine and I BLEW through carbon blocks. Like insanely fast. I've since switched to a Big blue which is a little spendy up front but lasts a very long time.

 

[greetl01]

Replace sediment filter when pressure drops 10% across filter.
Replace carbon when it shows breakthrough chlorine.
Replace RO membrane when TDS removal is less than it's rating. Mine is 99% so I expect 0 TDs after running a few minutes
Replace DI when color change is full or anything but 0 TDS coming out.

I've processed well over 10,000 gallons on my current membranes.

Zalick is doing it the correct way, but that way is a lot more inconvenient so manufacturers came up with the 3 to 6 month rule. The pre-filters only job is to protect the RO membrane. The sediment filter takes out the larger particles so the carbon and ro membranes do clog up prematurely. The carbon filters main job is taking out chlorine because chlorine (not chloramines) will destroy the ro membrane. The membrane then should take out at least 95% of everything else with the DI removing the rest. That is why you should never say your RO unit is working just because you are getting 0 tds from your unit. If we both have the same unit and my tap water is 400 tds and yours is 100 tds and we are both getting 8 tds water after the ro membrane, there is problem. I'm within spec because I'm running at 98% but you are not because you are at 92%. We would both be getting 0 tds water after our DI so if you were just doing an analysis based on that reading you would say both units are doing great.

You will see a gallon rating on a lot of the carbon blocks. This is based on a certain amount of chlorine in the water. You would need to know how much chlorine is in your water and do some algebra to come up with how many gallons that carbon block would last for you. I also don't go cheap on my pre-filters. My sediement filter cost about 2/3 of what my ro membrane cost but I wanted a very low micron rated filter.

Very important for anyone on treated municipal water to find out if they use chlorine and/or chloramine and how much. Then choose your carbon block based on that information. They have two ratings for how much chlorine and chloramine they can process in total gallons of water passed through the filter. Some can handle a lot of chlorine and very little chloramine. Some can handle both very well, hence the importance of knowing what is in your water. Then it is a simple matter of calculating how much total water you send through the filter to determine how long it can go before replacement. To do that collect both processed water and wastewater for a short period of time. Calculate how much total water it takes to get a gallon of RODI. So for example for example you send 5gal through the filter for 1gal of rodi and your carbon can process 10,000 gallon, you can get 2,000 gallons of rodi max from the carbon block. Probably best to replace a little before that though.

@zalick @Shirak @Opus


Took your advice and ordered a gauge, but I’m afraid to start cutting all Willy nilly. If you could please take the time out and assist me I’d appreciate it. (Or anyone who happens to see this thread)

my red tube is waste, the blue is tap water in. I only bought one (wasn’t sure if I needed one for every filter) I THINK the gauge goes between the RO (green label) and DI (brown label). Is that right?

 

[zalick]

@zalick @Shirak @Opus


Took your advice and ordered a gauge, but I’m afraid to start cutting all Willy nilly. If you could please take the time out and assist me I’d appreciate it. (Or anyone who happens to see this thread)

my red tube is waste, the blue is tap water in. I only bought one (wasn’t sure if I needed one for every filter) I THINK the gauge goes between the RO (green label) and DI (brown label). Is that right?

I'm colorblind....

You should put the gauge between sediment and carbon. With a single gauge you should note the pressure when you install a new sediment filter. Then when pressure drops 10% from the starting pressure it's time to change sediment filter.

I have two gauges, one on each side so I just look at the difference.

For the carbon you can change every 6 months. Or you can use a test strip on waste water and change carbon as soon as you measure chlorine. Sometimes your carbon will exhaust in less than 6 months depending on how much chlorine or chloramine in your water. That's why I like testing every time.

 

[greetl01]

I'm colorblind....

You should put the gauge between sediment and carbon. With a single gauge you should note the pressure when you install a new sediment filter. Then when pressure drops 10% from the starting pressure it's time to change sediment filter.

I have two gauges, one on each side so I just look at the difference.

For the carbon you can change every 6 months. Or you can use a test strip on waste water and change carbon as soon as you measure chlorine. Sometimes your carbon will exhaust in less than 6 months depending on how much chlorine or chloramine in your water. That's why I like testing every time.

Thank you!