400 tds water rodi filter

[greyhunter]

Hi i want to start a reef tank, coming from freshwater i always just used tapwater with no chlorine in it. My water has a tds of roughly 400 tds. Would a 4 stage rodi system be enough to get my water safe enough to use for a reef aquarium?

 

[Formulator]

Hi i want to start a reef tank, coming from freshwater i always just used tapwater with no chlorine in it. My water has a tds of roughly 400 tds. Would a 4 stage rodi system be enough to get my water safe enough to use for a reef aquarium?

I ran a 4 stage for many years and my city water is about 340 ppm. Only recently did I actually test the TDS and find out I was getting about 15 ppm residual TDS coming out. Added a separate 5th stage of DI resin to bring it the rest of the way down, but I suspect this would still be needed even with a 5 stage system since it is likely pulling out nitrates and phosphates that wouldn’t be helped by the additional pre-filter in a 5 stage RO system anyways.

So, the short answer is yes, 4 stage is probably fine, but depending on the specific contents of your water, you may need an additional DI filter.

 

[Jekyl]

I would go 5 stage. Reefs become harder when you are forced to start guessing.

 

[Extremeengineer]

My tap is 300, output from 4 stage is 0. If, or rather when, I buy a new RODI set-up, I will look at some criteria I simply did not know to look for the first time around. One, I will look for a better rejection rate, like the BRS Water Saver models that claim 1.5:1, while my current unit claims 3.5:1. It just stinks on city water I pay for to watch 3.5 gallons run down the drain to make 1 gallon of RODI. There are only so many plants I can water with runoff. Two, I will get one with a pressure gauge, that is a decent indicator of filter life, same with dual inline TDS meters, I like to see what is coming in and out.

 

[greyhunter]

I ran a 4 stage for many years and my city water is about 340 ppm. Only recently did I actually test the TDS and find out I was getting about 15 ppm residual TDS coming out. Added a separate 5th stage of DI resin to bring it the rest of the way down, but I suspect this would still be needed even with a 5 stage system since it is likely pulling out nitrates and phosphates that wouldn’t be helped by the additional pre-filter in a 5 stage RO system anyways.

So, the short answer is yes, 4 stage is probably fine, but depending on the specific contents of your water, you may need an additional DI filter.

Its mostly composed of minerals like calcium and magnesium i have really hard water

 

[Formulator]

Its mostly composed of minerals like calcium and magnesium i have really hard water

Me too (good ol’ Missouri limestone), but the nitrates and phosphates are what I assume made it through because my Ca and Mg were never a problem over the 6 or so years I ran a 4 stage system with apparently 15 ppm getting through.

 

[Buckeye Hydro]

Consider 4 stages (sediment, carbon, RO, DI) a default configuration. Add additional filters only if needed.

Don't fall into the trap of thinking "more stages is better." It can be, but that is not necessarily the case.

Don't use a system with two membranes plumbed in series unless you have soft (or softened) water.