Good rodi filter for 450 rodi water?

[greyhunter]

Hi i would like to start a reef tank (15 gallons) and i’m looking to buy a rodi filter so i dont need to buy rodi water from my lfs. I would need to make like 4/5 gallons a week i think for top off and water changes. The thing is i have really high tds readings like 450/40 tds would a 4 stage rodi filter make it 0 or near to zero so its reef safe? The picture is the one i’m looking at currently. I know the ro membrane is going to be changed a lot but i dont need that much water so it compensates right? Or am i missing something? Thank you in advance!!

 

[KrisReef]

The DI resin is what needs to be replaced, the ro membrane can last a long time before it needs to be replaced. This filter should work.
The information that you didn't provide is what is the rejection rate for the RO filter. The amount or resin that gets used will be different according to the percentage removal of TDS that the membrane provides. Rejection rates of 98% will leave very little ions to eat the resin, vs rejection rate of 90%, or 95% but we can't guess how the membrane will perform without the specifications of the RO membrane rejection rate?

 

[tharbin]

What @KrisReef said...

I have TDS in the 700 range and use a 4 stage. Get a membrane with 98% rejection and pick up an extra DI cartridge. I only get about 200-250 gallons from a DI cartridge before it is exhausted. If you get an expensive unit with a 90% rejection you will go through DI much faster. If the unit is rated at 75 gallons per day it is probably a 95-98% rejection membrane and good enough. Don't get a 100 gallon rated single-membrane unit as that will have a lower rejection rate.

The extra stages, beyond 4, give you other possible benefits. Some have an extra carbon block stage which helps if you have Chloramines in your water or it may have 2 DI stages.