Hydrometers stink

[ninjamini]

I own 2 hydrometers. A coralife and a marine enterprises. Both stink. I just had a auto top off malfunction that dumped almost 2 gallions of ro/di into the system. They are both still reading 1.026. Just not possible. I want a Pinpoint Salinity Monitor. Anyone have one? Are they good or overpriced?

How about a Hanna Instruments Testers for PH and Temp? Worth the money?

Hey of you have either laying around that you want to sell or trade...

 

[illal]

what you want is a refractometer

 

[ninjamini]

<a href=showthread.php?s=&postid=9418191#post9418191 target=_blank>Originally posted</a> by illal
what you want is a refractometer

From what I herd they can be just as inaccurate.

 

[instrance]

Hmmm, My refractometer works great. But any hoot. I guess everyone has there opinion :-O

 

[racermike27]

The refractometers are reliable once they are calibrated with the correct fluid. You cannot use just regular RO/DI to calibrate. I did mine this way originally and it was off by a few points.

There is instead a liquid that can be purchased that has a known salinity value that is set by a standard. This can then be used to calibrate the refractometer. Rogger knows the name of the liquid and where to get it. I was able to get some from him and it has worked out pretty well for me.

 

[illal]

regular distilled water shouyld work since it has a salinity of 0 :hammer:

 

[zigz]

<a href=showthread.php?s=&postid=9418698#post9418698 target=_blank>Originally posted</a> by illal
regular distilled water shouyld work since it has a salinity of 0 :hammer:

agreed

 

[ninjamini]

Where is a good place / cheap place to get one?

What about the ph tester?

 

[illal]

cheapest place would most likly be online

 

[ninjamini]

Anyone use this one? Or is there a better place / better priced one out there?

http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=9957&N=2004+113761

 

[racermike27]

There was a write up on the use of regular distilled water being used somewhere here on reef central and it was said that although it is zero there is no real guarantee. Using a precalibrated liquid will definitely ensure better results.
When I did mine with my R/O the TDS tested 0 on two different meters. So mine would theoretically be the same as using distilled right? When I tested the TDS of distilled it was something like 11-13.

For this reason I think it is better to use the calibrated liquid. An instrument is only aas good as its calibration IMO. I did check my Salinity before and after using calibrated liquid.
Before it was at 1.022 and after I was at 1.026 so there is some difference.

 

[racermike27]

I got my refractormeter from marinedepot

It was like 80 or so. It has the auto temp compensation but it does not have an internal light.

 

[compulou]

<a href=showthread.php?s=&postid=9419037#post9419037 target=_blank>Originally posted</a> by racermike27
There was a write up on the use of regular distilled water being used somewhere here on reef central and it was said that although it is zero there is no real guarantee. Using a precalibrated liquid will definitely ensure better results.
When I did mine with my R/O the TDS tested 0 on two different meters. So mine would theoretically be the same as using distilled right? When I tested the TDS of distilled it was something like 11-13.

I consider myself somewhat knowledgeable of our beloved hobby, but what does TDS readings of water have anything to do with Salinity readings of a refractometer?

I myself have a refractometer I bought off of E-bay a couple of years ago for like $35.00 and I've only had to calibrate it twice with distilled water. It has worked flawlessly.

 

[jeffbrig]

<a href=showthread.php?s=&postid=9418698#post9418698 target=_blank>Originally posted</a> by illal
regular distilled water shouyld work since it has a salinity of 0 :hammer:

In theory, it should work that way. In real life it doesn't, because the manufacturers of inexpensive refractometers lack the quality control to guarantee that prisms are accurately ground and placed inside the refractometer. In essence, you can end up with a "slope error" where the change in reading doesn't match the change in salinity at different levels. And the amount of error, if any, can vary unit to unit.

My $45 refractometer was dialed to 0 with RO/DI water when it was new. I then ran my tank at 1.025-1.026. When Randy Holmes-Farley started warning everyone about this several months ago, I mixed up a DIY calibration solution that should have read 1.026, yet my refractometer read 1.022. I reconfirmed that it read 0 with RO/DI. Still did. My refractometer was off by .004 when reading normal saltwater levels. :eek2: :eek2:

I then bought a Pinpoint salinity meter, and the calibration fluid that came with it also confirmed the error in my refractometer. With the refractometer dialed in to 1.026, it is now safe to use to measure normal salinity, but I would not trust it to do hyposalinity, since it will still misread at that level.

 

[racermike27]

Thanks JeffBrigg. That is exactly what I meant to say.