How much TDS is acceptable?

[divetoday]

I was surprised to test my TDS after making 15 gallons of ATO to see it at 12. I generally run between 0 and 2 at the most.

I have changed out my resin and gotten the TDS back down to 0, but I wonder if I need to throw out the 15 gallons of RO/DI I just made or if I can still use RO/DI that has a TDS of 12 on a mixed reef?

Thanks!

 

[DarkTang]

Depends... I check for po4... if it’s zero then it’s still good

 

[cromag27 Verified Sponsor]

anything above 0 and i’m changing filters. this will vary depending on the water quality in your area. we have nasty water in az.

 

[cmcoker]

I'd chuck it, maybe pump it into the washer and do a load of clothes so I felt a little better about it.

 

[lapin]

I was surprised to test my TDS after making 15 gallons of ATO to see it at 12. I generally run between 0 and 2 at the most.
I have changed out my resin and gotten the TDS back down to 0, but I wonder if I need to throw out the 15 gallons of RO/DI I just made or if I can still use RO/DI that has a TDS of 12 on a mixed reef?
Thanks!

Could it be from something like salt contamination in your ATO container?

 

[divetoday]

Could it be from something like salt contamination in your ATO container?

Good point, but not in this case.

 

[JoshH]

Good point, but not in this case.

Do you know what your TDS is out of your membrane??

Personally I'd just toss it, it's easier to make new water.

 

[theMeat]

Changing the resin will get the numbers down, but asking resin to remove that much and you’re going to use up a lot of resin fast.
Check filters and membrane
I’d toss the water, or use it for something else

 

[JoshH]

Changing the resin will get the numbers down, but asking resin to remove that much and you’re going to use up a lot of resin fast.
Check filters and membrane
I’d toss the water, or use it for something else

+1 on this.

 

[divetoday]

Hmmm... the three filters and the membrane were all changed about three months ago. Not sure how to check out of the membrane, will have to look into that.

 

[divetoday]

Hmmm... the three filters and the membrane were all changed about three months ago. Not sure how to check out of the membrane, will have to look into that.

 

[Kirschy17]

Answer to your question: if u wanna use it, do it.

12 tds compares to water with some leftover pieces of food or whatever. U do add some po and na but u do that with feeding anyways. If you are scared your tank wont be able to deal with additional “waste” added then make new water. I had no DI resin for the first 9 months and had no issues besides very little cyano. I had like 200 tds.

 

[Gareth elliott]

Are you using a flush valve? Sometimes buildup occurs on membrane without one. And tds exiting the membrane can exceed the ability of the resin to remove. Honestly i would be more worried the 12tds was calcium than po4 or no3.

 

[KStatefan]

Hmmm... the three filters and the membrane were all changed about three months ago. Not sure how to check out of the membrane, will have to look into that.

Figure out your rejection rate.

(Tap Water TDS - Permeate Water TDS) / Tap Water TDS

When the rejection rates start to go down replace the membrane.

 

[lapin]

Hmmm... the three filters and the membrane were all changed about three months ago. Not sure how to check out of the membrane, will have to look into that.

To test your membrane. You need to test the water entering into it then the water exiting out and compare it to the membranes stated rejection rate. I purchased an inline meter with 2 sensors to do this.

 

[theMeat]

Hmmm... the three filters and the membrane were all changed about three months ago. Not sure how to check out of the membrane, will have to look into that.

Checking the membrane explained by op.

If filters and membrane were changed 3 mos ago, then it looks like it’s one of these three things, or combination of....
-You don’t shut off water supply going into unit when not in use. You use a float switch of valve on product line to turn off unit. Which relies on a hi/low valve to shut the unit which is not there or not working properly. This will allow water to keep flowing through canisters that is exiting waste line.
-Wrong combination of filters, pre-membrane, for your particular contaminates.
-Not enough psi for the membrane you’re trying to use

 

[theMeat]

Oh, and size of flow restrictor, membrane, and psi all need to play well together as well

 

[cmcoker]

Answer to your question: if u wanna use it, do it.

12 tds compares to water with some leftover pieces of food or whatever. U do add some po and na but u do that with feeding anyways. If you are scared your tank wont be able to deal with additional “waste” added then make new water. I had no DI resin for the first 9 months and had no issues besides very little cyano. I had like 200 tds.

Personally, I am not worried about nitrate or phosphate being part of a 12 TDS, I dont think those even shown in the TDS, iirc. So I dont feel it is accurate to say that it's like leaving a piece of food in the water, or like adding extra "waste".

For my water supply, I'd be worried chloramines where breaking through and would test for that. But I would be most concerned about metals, like copper, tin, etc. Since I do not know what exactly that 12 or 15 ppm of "stuff" is, I would not chance it and I'd do laundry, or clean pumps. I wouldnt add the water to my tank, but I am very risk averse.

Some people will get by with adding tap water to their tank, some will need a more robust rodi system to deal with their tap water. All of us have very different water supplies depending on where we live. For example, even your next door neighbor may have older pipes and "worse" water, or I've read many Arizonans have to deal with very high TDS, like 600 or 700 TDS! We all have different risk tolerances as well.

 

[divetoday]

Checking the membrane explained by op.

If filters and membrane were changed 3 mos ago, then it looks like it’s one of these three things, or combination of....
-You don’t shut off water supply going into unit when not in use. You use a float switch of valve on product line to turn off unit. Which relies on a hi/low valve to shut the unit which is not there or not working properly. This will allow water to keep flowing through canisters that is exiting waste line.
-Wrong combination of filters, pre-membrane, for your particular contaminates.
-Not enough psi for the membrane you’re trying to use

I didn’t know that leaving the water supply to the unit turned on was a problem. I definitely do that, so I will try turning it off between uses and see if that helps. Thanks for the tip.

 

[theMeat]

I didn’t know that leaving the water supply to the unit turned on was a problem. I definitely do that, so I will try turning it off between uses and see if that helps. Thanks for the tip.

Not a problem if hi/low valve is working properly