So like everybody in Phoenix, my tap water stinks. My TDS out of the kitchen faucet is reading over 700 right now, so my water before it hits my DI canister is usually in the high 40's to 50's. Currently I am having to change my DI resin bi-weekly, and sometimes weekly which is getting ridiculous and expensive. So my question is, if I put another 96% rejection RO stage on after the initial 5 would that get my TDS down to a level reasonable to run through the DI? I'd appreciate hearing from anyone who has tried this, or knows from expertise that it would fail and why. I use my RO waste for watering my plants so I'm not real concerned with additional run-off since I will just dump it on the flower beds that would be getting watered anyway. Thanks for the input.
RO Question..Double RO?
- Thread starter ksigaekdb
- Start date
Your issue is going to be the pressure behind your product water going into the second membrane. If you are running a standard 4:1 waste to product ratio, you are going to be getting 1/4 of 1/4 or 1/16 product water.
Most systems that run a dual RO setup use the waste or brine output from the first membrane into the second RO membrane, then join the products of each RO membrane to increase output. However, this doesn't help your TDS reduction (it can actually make it a little lower total percentage wise).
I don't know that the water output from the first RO is sufficient to pass through a booster pump into the second membrane, but that could be an option.
Most systems that run a dual RO setup use the waste or brine output from the first membrane into the second RO membrane, then join the products of each RO membrane to increase output. However, this doesn't help your TDS reduction (it can actually make it a little lower total percentage wise).
I don't know that the water output from the first RO is sufficient to pass through a booster pump into the second membrane, but that could be an option.
Sammykonga
Member
If I were you, I would get a new membrane. 96% rejection is pretty low. It would be fine for drinking water, but it's marginal at best for reefing. You can purchase 98% membranes from BRS or Spectrapure. The added 2% will double the life of your DI and cut in half the incoming TDS to the DI. Additionally, you could take it a step further and purchase a 99% membrane from Spectrapure for even better results, they just cost a little more. Good luck figuring out a solution! Happy Reefing!
azjohnny
Active member
Your TDS after your membrane is really bad around 93% rejection . I would check your water pressure and make sure it is at least 60 psi (I run mine at 100 psi with a Spectrapure Maxcap and 99% rejection membrane) My incoming TDS is around 700 and and out going around 7
The higher water pressure will also increase the water production
The higher water pressure will also increase the water production
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