RO vs RODI

[rw135]

Hi there, new to posting.

Is there any difference between RO water at 0 TDS and RODI water at 0 TDS? I run my water filter system and found that my RO comes out at 0 TDS already. Do I "get" any advantage with the DI if it's already at 0?

Thanks.

 

[lmforbis]

If it is truly 0 TDS there probably isn't a need for DI resin but it may not always be 0 TDS. There could be seasonal differences in dissolved solids in your water.

 

[rw135]

Thanks. The line after the RO filter reads 0 on the TDS meter, so I didn't think I needed to go thru the DI.

 

[pegasus]

Thanks. The line after the RO filter reads 0 on the TDS meter, so I didn't think I needed to go thru the DI.

If it's always 0, then you certainly don't need DI. That's a pretty rare treat... lol!

 

[rw135]

If / when the readings start moving above 0, that should mean it's time to change the pre-filters? or start flowing to the DI and check and see if that moves above 0.
My input reads are in the 130's TDS range.

 

[bang guy]

You may as well just send it through the DI. The cartridge will not be used if there's nothing in the water and will last a long long time but if anything ever starts to show up it will remove it.

 

[pegasus]

You may as well just send it through the DI. The cartridge will not be used if there's nothing in the water and will last a long long time but if anything ever starts to show up it will remove it.

+1. Better safe than sorry.

 

[rw135]

Thanks for the advise.
I guess sending it thru the DI wouldn't use up the resin if it was at 0 in the 1st place.

 

[2quills]

Once the filters start getting some use the tds will start to climb. I'd still recommend a DI stage.

You're lucky. Our city water is so nasty I usually have 14-18 tds after the membrane. Even on a fresh one.

 

[streamer]

I only run a RO unit, my tds are about 10ppm and it feeds 2 tanks, a 125 gal fowlr w/55 gal sump and a 75 gal mixed reef w/55 gal sump and my tanks are AWESOME... no issues.. oh, in the fowlr I run a VERY heavy bio load and I tend to over feed..and to be honest, there is probly a heavy bio load on the 75 as well...

 

[snakeblitz33]

I would personally run one just in case there are any changes. If there is, then you should visibly see it as the DI resin changes color.

 

[rw135]

At what point does one start seeing a "rise" in TDS. Does anyone have a rule of thumb for the range a filter will last??? I've only had the filter system for about 9 months now.

 

[streamer]

Our water is not the best so I automatically change mine every 6 mths, better safe than sorry...cheap insurance...

 

[bang guy]

Right, the cleaner the source water the longer the filter cartridges will last. I also replace sediment and carbon every 6 months. The DI is replaced once I detect TDS over 1. RO is every few years depending on how it's working.

 

[pegasus]

Fortunately, the RO membrane... which happens to be the most expensive component... should last about 3 years. It depends on your filter change routine, and if you use a flush kit. Dirty or leaking filters and no flush kit will kill the RO in short order.

 

[snakeblitz33]

My tap water TDS when I bought my unit was anywhere from 500 to 999+ and the filters lasted anywhere from two to three months...

Then I moved and my tap water TDS sits at around 250 TDS and the water company does a chlorine burn three times a year, so I still have to replace my filters every three months.

 

[MarkShimala]

My neighborhood has a community well and we have hard water at a 17 grain and my TDS before my softener is about 470 tds and after my DI it is 0. I havent checked what it is after my RO membrane...I need to hook up the meter to it. I know I had to replace my DI resin after the first 50 gallons. I added a 2nd DI chamber now. Thats the beauty of the RO units....you can upgrade them super easy and pretty cheap. My unit cost me $85 on eBay for a 4 stage and I added the 5th stage for $22.