Soft Water

[BJ Mac]

I am in the process of setting up a new 220 gal. Reef Tank. My concern is I have a whole house sodium base water softener. I have read and been told that using the RODI will not remove the sodium and could cause me problems with the setup. I was told by one major supplier that at best I may get the TDS down to 5. Anyone had this experience?
Thank you for any advice and or guidance.

 

[kharmaguru]

I'm not sure why they are saying that. A softener improves the performance of RODI and actually makes the membrane last longer. I've been on a well with a water softener for 20 years, my TDS is usually 1 coming out of the membrane. What is your starting TDS?

 

[BJ Mac]

Good evening and thank you so much for the response.
I will have that number for you in a day or so, I realized yesterday that my meter was not working. It's old so I have a new one in route.
To be clear, I was never told I could not have a successful Reef Tank, but I would be limited as to what I could put in it and the sodium could cause me some issues. This is because the RODI would not remove enough of the sodium that the water softener has put in the water. I was told it would be better if I could come directly off the well with that water. That's not going to be easy to accomplish.

 

[griss]

I’m with Sean (Kharmaguru). Quality RO membranes have a decent rejection rate and the hard/soft water shouldn’t matter that much…one may deplete the membrane faster than the other.

FWIW, is Sean’s getting 1 TDS after the membrane for comparison…I have hard water where I live and get 7-9 TDS after my membrane with optimal temp and pressure of the water.

 

[BJ Mac]

This is getting more interesting by the day! It looks like I might be ok to move forward with the order and setup. I will get the TDS and report back. I really appreciate all the help.

 

[kharmaguru]

To be clear, I was never told I could not have a successful Reef Tank, but I would be limited as to what I could put in it and the sodium could cause me some issues

Say of your total TDS, the calcium and magnesium make up 60. (I am making this number up for my example). Those are what get switched to salt in your softener. So 60 TDS sodium now. Say your membrane has 96% rejection, now your sodium is 2.4 TDS. Forgetting that your DI stage will make that number 0, the TDS of sodium in seawater is over 10000. Your 2.4 will make no difference at all...