TDS

[SassyAngel111]

Just wanted to find out, I was reading another post about TDS reading 90 from RO/DI unit, what I would like to find out we have very nasty water TDS's just from the tap is 240x10 and I can get my TDS down to 20 something with the RO and a inline DI filter, but after a couple of uses my TDS is up to about 120 or so.

My question is would the resin beads be better than the inline DI filter, or should I consider useing 2 DI filters or any other suggestions? TIA

[Steven Pro]

Going from 240 down to 20 TDS is a 91.67% rejection, which is not very good. I would get a better membrane and a standard 10" vertical DI cartridge add-on.

[Kurt_Nelson]

Originally Posted by SassyAngel111

...we have very nasty water TDS's just from the tap is 240x10 and I can get my TDS down to 20 something with the RO and a inline DI filter, but after a couple of uses my TDS is up to about 120 or so.

I'm confused by your "240x10" comment. Do you mean your tap TDS reading is 2400 ppm? Also confused because your inline DI filter uses resin beads anyway.

Even if it is 2400ppm, it still sounds like something is wrong with your RO membrane and you're sending high TDS water through your DI stage, drastically reducing the life of the DI cartridge. If there's a way to get to the water after the RO stage and before the DI stage, test it there and see how much the RO is taking out. Most likely it's not much.

[seaham358]

What GPD membrane do you use? Water pressure through the ro/di unit do you know it? I ask because you can get better performance out of a ro/di with higher water pressure.
I run dual DI's and it helps lower TDS and phosphates.
I agree with Steve on his post and a vertical Di housing is the way to go, the water goes up through the cartridge getting better use of the resin.
I got a booster pump and I went from changing out my resin every 2 months to getting almost a year out of it. My start TDS is not as high as yours. My buddy had a TDS of over 700 and after he got a booster he gets better life from the resin also.

[melosu58]

I also agree with Steve as the vertical DI will be better.

[SassyAngel111]

Ok guys I do have a booster pump, my membrane is for 75gl. I just tested my water and here are the results:
Plain tap is: 1720
from holding tanks 220
from DI 62
right from the Membrane 208
So should I just change out the membrane which is only 1yr old and get a vertical DI instead or what. I know I have not had any problems with my tank since I have gone from a 29gl to a 50 to a 90gl. The 90 has been set up for about 1 1/2 months now
My Parm are:
PO4 =0
NO2 = 0
NH4 = 0
Ca = 390
Alk = 10.6
Temp = 78.6 to 79.3
Sal = 1.027 useing a refactor.

Corals are doing great and so are the fish

[MT79]

Plain tap is: 1720

That is extraordinarily high. A "normal" TDS level that is on the high side is about 300-500. Have you calibrated your TDS meter lately?

[Kurt_Nelson]

I wouldn't doubt 1720 from Arizona. Most of that is pretty nasty stuff. (Sorry... no offense. I'm just from the land of very nice water in WA state! But people here still buy bottled water to drink. Go figure.)

[MT79]

It's only 300 or so in the Philly area, and we have crappy water IMO/IME. Some people online have <100 TDS from the tap. If Arizona water is that high, I would not drink the tap water.!
If your TDS really is that high, I think two RO membranes would be best(you may need two or more DI units as well). I've seen units using multiple RO membranes in the past. Otherwise you are going to blow through DI resin. Generally, the purpose of adding a DI to an RO unit is to get TDS down to 0. The DI is used to soak up what little is left that the RO will not.

[SassyAngel111]

Kurt, no offense taken, we are with a private water company and it is well water on top of that, the water company says there is nothing wrong with their water and it is safe to drink just from the tap (yea). I never thought about running two membranes, so I guess I will go searching the great wide web for another membrane and and a vertical DI unit. Thanks guys for the info.