Lost Salt - SOLVED

[NaCl_H2O]

Ok, here is a question I have been wanting to ask, but wanted to make sure I wasn't insane first?

Does salinity of aquarium water decrease over time? If so, why?

I am using a PinPoint salinity monitor that is on continuously. Periodically I calibrate it, and check it against a hydrometer - so I am fairly confident it is accurate.

I try to keep my salinity at 49.5 mS (1.024 SG). In a 24-48 hour period, my salinity will drop to ~48.5 (~1.0235), and I will add a little salt mix into the sump to plus it back up. I typically do this several times in between water changes, which I do once every two weeks.

I realize this is no big deal, but I am curious "Where is the salt going?" I don't have rediculous saltcreep problems, and I have an auto topoff that keeps my sump level VERY accurate. Maybe the water level in the tanks creeps upward in-between scrubbing the overflows and the top-off makes up the difference? Had not considered that until I was writing this post??

Any thoughts on this one?

[JimD]

lol,,,,,,, your skimmer is the culpret, it not only pulls organics, it also pulls salts that are attatched to the proteins...

[NaCl_H2O]

Hadn't considered that, thanks!!

Guess I need to taste my skimmate next time to see how salty it is :o

[GaryP]

Steve,

Are you sure your salinity meter is accurate. Are you testing with some other back-up method like a refractometer or hydrometer occasionally. They do malfunction. Just ask Scuba steveo. His salinity was up to 1.028 before he caught it.

I don't know how significant a source it may be, but salt creep could also be another source of salt loss. Here's another factor going the other way. Any additives you are using will have the tendency to increase your salinity. That would include 2 part, kalk, and your reactor effluent. Of course this is easily adjusted for in your water changes. Ideally, you will be taking most of this stuff out as fast as you put it in (mass balance). That may not be the case with 2 parts though. That's why I do an occasional large water change to keep it ionically in balance. Its a draw back to 2 parts but one I try to overcome until I'm ready to add a reactor.

[dan]

maybe the pugs are getting a drink before bed time :-D :-D :-D

[NaCl_H2O]

Actually, and increase in water volume would be more appropriate for the pugs ... hum, I wonder if they might be "dilluting" my salinity :(

Gary, I think the monitor is accurate. I just calibrated it to make sure, and it checks out against a swing arm Hydrometer.

[GaryP]

Now you probably have the only calibrated salinity meter in South Texas.

Congrats!

[NaCl_H2O]

Now you probably have the only calibrated salinity meter in South Texas.

lol ... come on Gary, I bet you calibrate yours every night before you go to bed ;)

[RobertG]

My pinpoint fluctuates all the time when I run it on constant. I found that using it only when needed, it reads correctly.

[NaCl_H2O]

Well, the mystery is solved :angry :angry :( :(

I just calibrated this $#$@#!#@% thing like two weeks ago, so I was "Trusting" it. When am I gonna learn to remain VERY suspicious of automation gear!!!!!!!!!!! Should of listened to GaryP (How many times have we all said that!)

My salinity monitor was apparently creeping out of calibration, maybe a dirty probe, maybe just crap for electronics? My salinity has climbed to 1.026+ when I finally thought "This ain't right"???

Slowly taking it down now ...

Pete, this is probably why the new stuff wasn't opening up nicely.

So, what is a RELIABLE device for measuring salinity? Maybe I'll just go back to the good old fashion floating Hydrometer :angry :angry :angry :angry :angry :angry :angry

[::pete::]

I just calibrated this $#$@#!#@% thing like two weeks ago, so I was "Trusting" it. When am I gonna learn to remain VERY suspicious of automation gear!!!!!!!!!!! ;)


So, what is a RELIABLE device for measuring salinity? Maybe I'll just go back to the good old fashion floating Hydrometer

Refractometer. :)

[C.Mydas]

Pete can do it by taste. ;)

[NaCl_H2O]

Pete can do it by taste. ;)

I don't like strange people licking my tanks ... Yes, Pete is strange ;)

[Polkster13]

Joshua,

The store is marked "closed for maintenance until Feb 15th". Hopefully it will be back up soon (as it is well past the 15th).

[GaryP]

ol ... come on Gary, I bet you calibrate yours every night before you go to bed

I'm a pretty much old school, low tech sort of guy. I'm still using the swing arm I got when I first got in the hobby. Of course I have calibrated it againt a borrowed refractometer. The only electronic equipment I have is a couple of Radio Shack thermometers.

What I think happens to most electronic probes is that they develop a bacterial film over them. That's not a problem with the thermometers because the bacteria transmit temp. just as well as water. They are 90% water, after all. However, when you are measuring an electrical current across the probes as is the case with a pH or salinity meter, it is a problem. I think the electrical gizmos are great, but not for continuous use. I used a Ph meter daily when I worked in a lab, but it got calibrated daily at 3 different standards (4, 7, 10). Most hobbyists are lucky if they calibrate theirs once a month, if ever, and then maybe only at one standard point. I think that for salt water it should be calibrated at 7 & 10 at a minimum since what you are measuring falls between those two points. Of course you really don't need accuracy to 2 decimal places like I did. The other problem, especially with pH probes is that they contain a solution of potassium chloride. We soaked the electrode in a KCl storage solution between uses so that it would stay isotonically balanced. I don't know what keeping a pH meter in saltwater does to the KCl concentration inside the probe bulb. The bulb is porous to ions and it might eventually lbecome unbalanced. Salt water does contain a fair amount of KCl but I'm not sure if it has enough.

BTW, the same thing would apply to the new ion selective probes for calcium and alkalinity that I have heard discussed here. They work something like a pH probe. They are not really new, been around for many years, they are just new to the hobby.

OK, I'm sure I have lost most everyone reading this by now besides Larry and Misti.

[NaCl_H2O]

OK, I'm sure I have lost most everyone reading this by now besides Larry and Misti.

Not at all! You get alot of grief on these posts, but only because WE ALL READ THEM :)

So, I am going to order a refractometer, but I want to get a GOOD one on my first buy, any suggestions? I'm leary of the swing arms - had two at one time and they read .002 appart from each other :o

Now I am also not wiling to trust my "Calibrated" PH Meter - Just calibrated it against 7 & 10 NIST, but had a hell of a time to get the cal stable going back & forth between standards (never got it perfect) - maybe due to the KCl issue you mentioned.

What is the most reliable/accurate way to measure PH? Other than a Salifert Kit?

Thx - Steve (aka: Always Learning)

[GaryP]

I'm going to go to a floating hydrometer. The most ccurate in my opinion. The only real negative is that you have to adjust for temp. but that just means reading the adjustment off a chart.

That's how we did it in the lab.

[NaCl_H2O]

I'm going to go to a floating hydrometer.

Can you buy those anymore? I had a really old one until about a year ago, but I dropped it and it became "Un Calibrated".

[GaryP]

You mean it became a lot of pieces of glass and lead?

Yes, you can buy them. I know where to find them in SA. Not far from your house. I need to get a 100 ml. graduated cylinder to go with it. The come in different ranges, you just need to get one that includes the 1.020 to 1.030 range. I've seen them on some fish sites too.

[NaCl_H2O]

You mean it became a lot of pieces of glass and lead?
You got it!



Yes, you can buy them. I know where to find them in SA. Not far from your house.

I assume you mean "Analytic Scientific", or maybe our nearby LFS (AA)?

[GaryP]

Yeppers, Analytic Scientific on Bandera. If you are going to get one there, give me a call.

[GaryP]

I don't see the right range on their website. They may have to order it.

[GaryP]

Here you go.

http://www.novatech-usa.com/s.nl/sc.2/it.A/id.3325/category.392/.f

[scuba_steveo]

I'm going to go to a floating hydrometer. The most ccurate in my opinion. The only real negative is that you have to adjust for temp. but that just means reading the adjustment off a chart.

That's how we did it in the lab.

Gary, are those better than this?
http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=REFRACT-PA&Category_Code=Hydrometer

Steve, I had the same problem. I would calibrate my pinpoint every two weeks and it still was reading off right after a calibration. Dang pinpoint, my salinity went up to 1.028. Anyway, I think I am goimg with a Refractometer.

[NaCl_H2O]

Steve, I think the point is that a floating Hydrometer is a good baseline to have around. It never needs calibration, other than temperature conversion from a chart. Works on bouyancy of saltwater.

[brewercm]

I have a refractometer and swing arm. I use the swing arm when making up new saltwater until I get close then switch over to the refractometer for getting it the same as the tank.




However, when you are measuring an electrical current across the probes as is the case with a pH or salinity meter, it is a problem.

This kind of makes you wonder if you might need to take out the grounding probe and clean it off every so often.

[GaryP]

As long as a floating hydrometer is clean it is the most accurate thing out there. Someone posted soething a while back about accuracy problems with hydrometers. I think it was Larry.