Picking up TDS in collection container

[Frtdrmrose7]

I have a 7 stage RODI and have two 50G food grade barrels I use for making water. I’ve been doing this for a while and my water out of my RODI is 0 TDS. I made water today and checked the water in my barrel and it had 135 TDS! I dumped it thinking something was leaching into the water. I started making water in my other one and even with an inch of water in the bottom I’m getting 5 TDS already.
Anyone run into this?

 

[KrisReef]

Interesting. Were those used food grade barrels? Either way, I can't imagine that much leaching from a food grade material?

I've noticed I get contamination from my son dipping out water to wash his car windows. Are your barrels covered, or open where stuff might drift in?

 

[Hondatek]

Could possibly be left over salt residue from mixing in the same barrel over a long period of time.

 

[Frtdrmrose7]

Interesting. Were those used food grade barrels? Either way, I can't imagine that much leaching from a food grade material?

I've noticed I get contamination from my son dipping out water to wash his car windows. Are your barrels covered, or open where stuff might drift in?

They are food grade and covered. I just dumped 50 gallons and started new water in the other one that was empty and I already have 5 TDS.

 

[Frtdrmrose7]

Could possibly be left over salt residue from mixing in the same barrel over a long period of time.

Could possibly be left over salt residue from mixing in the same barrel over a long period of time.

Should I try to wash them out and try again?

 

[cromag27 Verified Sponsor]

what tds meter are you using? has it been calibrated recently? any airborne pollutants? is the inline meter on your rodi reading 0 or are you using the same handheld as with the collected water?

 

[Frtdrmrose7]

what tds meter are you using? has it been calibrated recently? any airborne pollutants? is the inline meter on your rodi reading 0 or are you using the same handheld as with the collected water?

I have two TDS meters one on my R/O from BRS and second of the same (brand new) I’ve dismounted the one from my R/O and they have the exact same reading if I hold the probe under the stream of water coming into the barrels it’s 0 TDS as soon as it’s in the barrel I pick up TDS

 

[Frtdrmrose7]

To check the meter I just grabbed a water container and started making water. In the container it is 0 TDS, it must be salt residue in the others.

 

[cromag27 Verified Sponsor]

I have two TDS meters one on my R/O from BRS and second of the same (brand new) I’ve dismounted the one from my R/O and they have the exact same reading if I hold the probe under the stream of water coming into the barrels it’s 0 TDS as soon as it’s in the barrel I pick up TDS

holding a probe under running water isn’t that accurate. best to collect in a completely clean cup and then test.

i would clean out your barrels with water very well, then thoroughly dry. test again.

 

[Awesome Dennis]

Are these the same barrels you make your saltwater in?

 

[Frtdrmrose7]

Are these the same barrels you make your saltwater in?

Yes, I typically make and keep 20-60G of water on hand depending on any upcoming W/C’s On my tanks. (I do mix in these barrels)

 

[sde1500]

Not a surprise at all you're getting TDS readings measuring in a salt mixing container. Likely from residue on the barrels from previous batches of salt water, plus some salt creep that dissolved. And airborne particles that get in the water as soon as you open and look in. I'd doubt its anything to worry about.

 

[lapin]

Salt is what you are seeing, as stated above.

 

[Awesome Dennis]

You need to test in a clean glass seperating from you mixing container or if you have a Rodi only tank.

 

[Frtdrmrose7]

You need to test in a clean glass seperating from you mixing container or if you have a Rodi only tank.

I did that with my 5 gallon water jug, 0 TDS in there. I’m going to wash both barrels out and use one to hold 0 TDS water and the other for prepared saltwater.

 

[Frtdrmrose7]

I cleaned out and dried the barrels and now back to 0 TDS stored water. I guess it was salt residue. Thanks to everyone

 

[Buckeye Hydro Verified Sponsor]

Not a surprise at all you're getting TDS readings measuring in a salt mixing container. Likely from residue on the barrels from previous batches of salt water, plus some salt creep that dissolved. And airborne particles that get in the water as soon as you open and look in. I'd doubt its anything to worry about.

This is right on the money.
Remember even your aquarium is exposed to air and will therefore pick up dust etc. It is really not something to be concerned about.
If you have a handheld TDS meter, here's an interesting experiment. Take a cup of 0 TDS water and insert your meter. Let it settle at zero. With the meter still in the cup, put your clean finger in the water. The TDS will change. Remember that you are reading TDS in parts per million - ppm - so it is very sensitive.

Russ