conductivity probe

[recife111]

I calibrated my conductivity probe.

reading of my tank is 1.021 with probe
with refractometer reads 1.025.

so why is the probe so far out? the refractometer will be correct as it is vegee refractometer and all my other refractometers read the same.


recalibrated the probe and i get the same result.

 

[BigAl2007]

Here are some links for you to look into

Why NOT to trust a Refractometer against a profiLux

or this one may be better
So salinity - This will take a while

 

[AQD_ottawa]

Well sorry to say as the thread links state, refractometers are not designed to read Natural salt water, the extra elements in NSW throw the refractive index out by quite some way.

The amount of wrongly calibrated refracts out there worries me a lot so many think they have the right salinity but they simply do not.

The conductivity probes are not effected by the external forces of other elements in water so will always read accurate AKA the GHL salinity probe.

Calibrate both the GHL salinity probe and refract to a known NSW solution such as fauna marin multi ref test solution and they will read pretty darn close.

Why use the NSW solution for the GHL probe as well?

Your trying to get the refract to match it so you have to use the same solution for both.

As of June we will be promoting in our Aqua Digital Forum refractometers not only pre calibrated to NSW but also available with 2ml of FM multi ref solution for future calibration.

 

[recife111]

Pretty sure the probe is wrong.

re tested and recalibrated results.

probe 1.022
Tropic marin hydrometer 1.0245
vegee refractometer 1.025
cheap hydrometer 1.024

will look to get new calibration solution to re test

 

[AQD_ottawa]

100% no, sorry I have been down this road sooooooo many times

Look at your own statement "veggie refractometer" NOT NSW refractometer

As long as you calibrate exactly as I have stated in my guide it will read within .001 SSG give or take

if you still want to doubt it then use the (what I like to call) the doubters offset adjustment, but you then are not getting the true benefits of the highly expensive and highly accurate GHL probe.

if I had a dime for everytime we have had this thread on here LOL

 

[recife111]

Look at your own statement "veggie refractometer" NOT NSW refractometer

But you missed the Tropic marin hydrometer 1.0245
I would have thought the LAb grade hydrometer would be pretty spot on.

 

[AQD_ottawa]

I personally have never heard of a "lab grade" hydrometer. I also doubt their accuracy always have done, long before GHL came along.

But which ever way you want to spin the dice a refractometer is not designed for NSW and for it to be accurate you have to calibrate it to NSW engineered solution, its a hard fact that cant be argued and there is heaps of things about this on Reef central.

The other thing is you are mixing two different kinds of technology - one is effected by external elements such as trace elements etc etc the other being the conductivity probe is not effected.

Everyone will want to believe what they want, this is why GHL put in the doubters offset, which I kinda disagree with being present really, but at the end of the day why spend so much on a probe you wish to distrust against much cheaper devices.

I think i have said enough on the topic as I am just repeating myself from other threads . All those threads ended with properly calibrated refractometers and happy GHL owners

 

[recife111]

http://www.tropic-marin.com/web/english/produkte/araeo.htm

 

[AQD_ottawa]

Not quite sure what you are wanting us to say?

Trust what you feel comfortable with, but there is no doubt at all a conductivity probe will always read more accurate than any manual devise, more so when you are dealing with a probe that comes with certified accuracy and a tag to match it.

If you want to use the GHL probe then calibrate it exactly as I have described and it will be accurate, there is little more I can say really.

 

[recife111]

AQD_ottawa

Look at your own statement "veggie refractometer" NOT NSW refractometer

boomer wrote

We now have 2 in this hobby. Many of us for the last year have **Assumed**, me too, that the Vee-Gee from TGF and the Vital-Signs from F & S were NaCl. I just talked to the head-nut refract guy and they too are real seawater refracts

So the vee gee is a NSW refractometer?

 

[AQD_ottawa]

Any refractometer IMO can be a NSW refractometer you just have to calibrate it to be one, its not rocket science

 

[hlsooner]

Funny how this debate rages on. As pointed out above, calibrating with NSW will make most available instruments do the job. My GHL salinity probe went out after 2 years and I just can't bring myself to part with $200 to replace it. I just don't find my salinity moves very much and don't need it live monitored. I also own a Vee Gee Scientific (not veggie :spin1 refractometer which provides exceptional accuracy, especially when calibrated with local NSW.