RO/DI questions

thumped · May 9, 2021

Yesterday I installed a 6 stage RO/DI 75 GPD system with an auto flush, tank float, and booster pump that feeds a 500 gallon storage tank. After 24 hours I have a bit over 100 gallons according to the marks on the tank. The TDS meter has been crazy, but just found that they were installed in the wrong direction and started reading 1 TDS after running for 5 minutes.

My source is well water and has 130 to 190 TDS depending on the time of year the lab test the water.

I will be using around 50 gallons of water 4 to 6 times a week. I was planning on cutting off the unit around half a tank before turning it back on. Is it worth doing this and if so what's the best way to shut if down?

I feel that I have done a good amount of reading on RO/DI, but I'm sure there's more to read. Any suggestions?

Thanks, Thumped

AutumnReefs · May 9, 2021

Make sure you have a DI bypass when flushing. This saves you lots of DI resin. I did this after seeing someone mention it on another thread and it works well.

Dunc · May 9, 2021

thumped said:
Yesterday I installed a 6 stage RO/DI 75 GPD system with an auto flush, tank float, and booster pump that feeds a 500 gallon storage tank. After 24 hours I have a bit over 100 gallons according to the marks on the tank. The TDS meter has been crazy, but just found that they were installed in the wrong direction and started reading 1 TDS after running for 5 minutes.

My source is well water and has 130 to 190 TDS depending on the time of year the lab test the water.

I will be using around 50 gallons of water 4 to 6 times a week. I was planning on cutting off the unit around half a tank before turning it back on. Is it worth doing this and if so what's the best way to shut if down?

I feel that I have done a good amount of reading on RO/DI, but I'm sure there's more to read. Any suggestions?

Thanks, Thumped

200 to 300 gallons of RO/DI water each week it a lot of water. I would keep the 500 gallon tank full.

jassermd · May 9, 2021

Which brand RO/DI did you purchase? The ones from BRS have auto shutoff valves preinstalled, so there is no worry in stopping/starting the water. If you don't have one on your RO/DI system, then they can be purchased and installed.
If you're concerned of TDS creep, then letting your tank fully drain or 1/2 drain before refilling will keep that in check. Given the volume you're working with, I don't think it will be a problem.
You may want to add another DI stage if you're that concerned.

thumped · May 9, 2021

Yes the DI is bypassed when flushing.

I'm not 100% sure on my water usage yet as it's for the feed water of a new steam boiler that's should be done getting installed Friday. It's to run some commercial equipment. Sorry not fish related. I'm being told I should use 20 to 30 gallons of makeup water a day that I run the boiler.

I got a 6 Stage Deluxe Plus 75 GPD RO/DI System - Bulk Reef Supply and yes has the shut auto shut off valve. I need to keep the TDS under 10 if at all posable.

jassermd · May 10, 2021

Given the high TDS of your well water, you may find it beneficial to pick up the 7th stage for the RO/DI. It will likely save you $$ in resin...
If you're concerned about TDS creep, then putting a low level (on trigger switch) and a high level (off trigger switch) like you mentioned is a good option. There are several options out there, such as the Tunze RO controller

RO Water Controller

Make RO Water production more convenient with Tunze's automated RO Water Controller! The Tunze RO Water Controller 8555 is used to regulate the water level in your fresh water storage container. It uses two float switches to control an electronic valve. When the water level drops below the...

www.bulkreefsupply.com

Whatever you choose, be sure to have a secondary backup mechanical off such as a float valve mounted above the digital switch.

thumped · May 10, 2021

@jassermd When you say 7th stage are you saying 1 DI Cation Resin Filter (+), 1 DI Anion Resin Filter (-), and 1 DI Mixed Resin Filter (+ & –) or are you talking about a second RO membrane?

Thank you all for your help so far.

jassermd · May 10, 2021

My pleasure. Yes... I'm saying exactly what you pointed out 1 DI cation, 1 DI anion, and 1 DI mixed.
My city water is running around 70-80 and I run the 6 stage water saver from BRS. My DI resin lasts around 4 months, so given your load, you may be better off with the extra DI stage. Should get you to 0 TDS consistently.