Lesson learned on Salinity

[d2mini]

So I've had a reef tank for 5 years... Been using the same plastic, low-tech, submersible salinity checker, that I'll bet most of you will say I'm careless for using.
However, Two cups of Red Sea coral pro in 4 gallons of Ro Di water has yielded the same measurements... Always. Hard to argue with consistency... And a successful tank.

So why should I have the high tech one, that needs calibrated, etc, etc... I'm open to the idea but hard to argue against positive results.

It's just a tool. Sometimes different tools are useful for mitigating risk, when one knows how to use said tool properly.
Redundancy can be a good thing.
If what you are doing is obviously working for you, then continue along.

I like my combo of refractometer and conductivity probe.
If I suspect one may be "off", the other is there to confirm.
And the refractometer can be used where the probe can not, due to the portability factor.

 

[salty150]

I wonder what the user error plus instrument error is on non-digital refractometers?

Exactly...

 

[Desmo996]

Agree on all counts. I'm sure it's not exact but since I've been consistent , it has enabled good results. Perhaps the results would be better if I had it exact, but surely there's a +\- range that we operate in. From a cost perspective, I thought it better to have calc and alk test equip. Since I focus there, everything else seems to stay in check. And my hobby funds have gone toward other equipment. Now that I'm getting more "advanced care" and certainly $$$ corals I need to reconsider my hydrometer.

Thanks for the article Randy. I look forward to reading it.

 

[Desmo996]

Ok, I read your article...great read, love the objectivity. Conveniently, BRS sells the portable refractometer at 10% off to temp... yes I'm sure google tells them people talk about their stuff (good for them).

So I do the pepsi challenge between my old hydrometer and my new refractometer... they were so close that I have to really strain to read the difference. I realize one is a gauge with large movements with guess-work spot measurements and the other is a finer instrument with exacting lines. Either way, all good for me. No regrets buying the refractometer since I'd be more than a little cranky letting expensive coral die because I was too cheap to buy a better tool.

Anyway, I wanted to thank you with a follow up.

Well, maybe it has been inaccurate all this time? lol
I tested two swing arms for an old article and one was quite inaccurate:
Chemistry and the Aquarium: Specific Gravity: Oh How Complicated! ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/2002/1/chemistry
from it:
So how do these hydrometers measure up? In my tank the water was measured to be S=35 ± 0.5 by conductivity. Using the Deep Six swing arm hydrometer I got readings of S=32.5 ± 0.5 at 81 °F and S=32 ± 0.5 at 68 °F. Using the SeaTest I got S=34.5 ± 0.5 at 81 °F and S=34 ± 0.5 at 68 °F.

 

[Rick.45cal]

I ordered a VEE GEE STX-3 to cross check my milwaukee digital refractometer and it came today. It's pretty easy to use, I calibrated it with 35ppt calibration solution (it was nearly spot on out of the box) and tested my tank. Amazingly it was exactly the same as what the milwaukee tells me it was. (I was actually relieved).

I'm glad I got the VEE GEE STX-3 I'll probably end up using it more than the digital one.