Total Dissolved Solids Questions

[curator]

I filled two 5 galllon containers las evening from two side-by-side RODI machines at Kroger. Using my TDS probe, one read 055, the other 085. I tested some RODI water I had purchased at a marine aquarium store and it read 041. The water in my tank was 010. I realized this moring that my probe probably needs to be re-calibrated...however, it is interesting that water from the two Kroger machines (Glacier?) read differently.

Has anyone used water from these machines - and if so, any comments?

Thanks,

John

 

[linda lee]

Curator;294850 wrote: I filled two 5 galllon containers las evening from two side-by-side RODI machines at Kroger. Using my TDS probe, one read 055, the other 085. I tested some RODI water I had purchased at a marine aquarium store and it read 041. The water in my tank was 010. I realized this moring that my probe probably needs to be re-calibrated...however, it is interesting that water from the two Kroger machines (Glacier?) read differently.

Has anyone used water from these machines - and if so, any comments?

Thanks,

John

Machines at Kroger are only as good as how often they change the filters. You'll get pretty inconsistent water from those machines.

And... when you say you tested tank water at 010, are you using your TDS meter in saltwater? I don't think you're supposed to?

 

[curator]

Yes - I wasn't aware one shouldn't.

 

[linda lee]

Curator;294856 wrote: Yes - I wasn't aware one shouldn't.

Well, I'm not sure. Someone with more TDS experience should reply, but we've personally never tested saltwater. RO water should be within safe range before you mix it, so there should really be no need.

 

[jmaneyapanda]

You cannot test TDS in saltwater, only freshwater. All the reading you got were not very good. Personally, out on my RODI, I never really get above 004, but would tolerate up to 010, but above that, I would change the inserts. If youre getting 040 and above from a LFS, ask for your money back. But calibrate the TDS meter first. Make sure, it is that high. The store amchine are sueless for our applications. Just my experience.

 

[derek_s]

Yeah, your readings are off, it seems.

Think about it, dissolved solids include minerals, and your salt water is full of minerals (salt, calcium, magnesium, etc) so actually a reading of saltwater should be off the charts.

 

[ralph atl]

The only exception on the store machines are that both Publix' in Flowery Branch & also the one in Snellville all tested below 10 everytime. Glacier water.

I've tested water at 3 or 4 lfs, and their readings were always very high, close to tap water.

I have since purchased an RO/DI unit. It is sooo worth it.

 

[linda lee]

mysterybox;294870 wrote: I have since purchased an RO/DI unit. It is sooo worth it.

+1 RO/DI pays for itself in no time.

Also ... many reefers produce more RO/DI than they can use. We always have enough to share and have given RO water to fellow reefers near us. There may be a reefer near you who would be willing to share excess RO and it wouldn't hurt to creat a post and ask. You could chip in from time to time on the cost of a new membrane and it would still be cheaper than buying from a LFS or grocery store.

 

[george]

If you purchased RO/DI water at an aquarium store and it wasn't just "RO" water, that reading is nuts. They should be changing their DI resin as soon as it reads much over zero.

As mentioned, though, the best way to ensure it's done right is to do it yourself with an RODI filter.

 

[skriz]

Curator;294850 wrote: I filled two 5 galllon containers las evening from two side-by-side RODI machines at Kroger. Using my TDS probe, one read 055, the other 085. I tested some RODI water I had purchased at a marine aquarium store and it read 041. The water in my tank was 010. I realized this moring that my probe probably needs to be re-calibrated...however, it is interesting that water from the two Kroger machines (Glacier?) read differently.

Has anyone used water from these machines - and if so, any comments?

Thanks,

John

Glacier water is not RODI water. ALso, their maintenance consists of chlorine backwashing. Filter replacement isn't done that often (the machines are not designed to create 0 tds water, they're designed to make drinking water.)

TDS stands for total dissolved solids. Anything disolved in the water will read as tds. Thus, testing saltwater is pointless since you KNOW you have dissolved solids in sw.

RODI should be 0 tds or really close to it. My unit never puts out anything above 0. If the pet store RODI is that high, go back there and talk to the manager.

 

[dakota9]

Walmart registered an 01 when I tested it. At 33 cents a gallon, its pretty cheap too. I'd gladly pay a reefer in my area something around that figure to pick up their extra RO......

 

[roland jacques]

ares;294913 wrote: Id expect a LFS to have a TDS meter to test their water with.

your readings are all over the place. perhaps the salt water exposure has corroded the probe and why its getting all jacked up readings?

2nd that

Your tank Saltwater should be off the scale, like over 5000 PPM TDS or just a error sign.

 

[darren24]

When you did your side by side readings were both containers clean? If one was used previously for say salt water and had residue it would make the reading different.

 

[oil_fan]

Darren24;295160 wrote: When you did your side by side readings were both containers clean? If one was used previously for say salt water and had residue it would make the reading different.

+1 on that.

I've tested my RO/DI water using a cup I just had around and it read something like 27 or so. I then grabbed a disposable cup that was still in the sleeve and retested and it read 0 this time.

So yes, the container has to be spotless.

 

[drnecropolis]

I get 0 tds out of my rodi..I think it was about $100 after shipping..
And agree with the tds in the water.. The few times I have ever stuck a tds meter in a tank all I got was 999.(High as it reads)