Refractometer Calibration /w RODI was off. What to do?

[ps2cho]

So I just tested my refractometer against RODI water and it was showing 4ppt. (washed the unit really well to ensure no residual salt so it was 100% clean).

 

Should I adjust the meter to reflect zero, or should I buy some actual 35ppt calibration fluid?

When I adjust for the 4ppt, my Salinity is now 1.022 instead of 1.026....so I am kinda concerned now.

 

Is RODI accurate enough to calibrate with?

[doppelganger]

if you want peace of mind then get some calibration fluid. Does it make a difference? Some would argue about it but yes, it can throw you salinity off a bit. The main point is consistency tho. If it's off by a bit it won't make that huge of a difference. There's plenty of other factors that can throw off a refractometer so it's a good idea to get some calibration fluid or make your own incase. I'm sure plenty of ppl here use plain freshwater to calibrate tho. Consistency is key.

[bonsaidarrell]

I would either buy the calibration fluid, or check it out at your LFS. Using RODI will calibrate it at zero, but not necessarily for 35ppt.

[ElmoC]

What do the instructions for the refractometer say to use? Most that I have seen require the use of a calibration fluid.

[m0nkie]

my ATC refractometer said only use calibration fluid... I've seen a lot of people failing with RO/DI water calibration. just buy a bottle on amazon.. $5

[jahoban]

I was using RO/DI for over a year for calibration will no issues at all. I purchased some 35ppt calibration fluid on a BRS order just to see if I was far off using just water. It turns out I was about .004 off. I am not sure if that makes a HUGE difference in the health of the reef but I was glad to know the true SG of my tank. Now I keep it at a proper SG at all times.

 

Jason

[aviator300]

My refractometer is a Marine Depot model and the instructions say to calibrate it with plain ole distilled water and it's been working great at 1.025 and 33

[ps2cho]

I received Sybon 35ppt salinity solution and it matches the same scale as when I recalibrated with the RODI.

 

So as of right now my salinity was actually 1.022 after the adjustment. I wonder if this is why I haven't seen much growth in corraline algae yet?

 

 

http://www.ebay.com/itm/350905529209?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

$7.

[iceet]

Can't hurt to have a second refractometer/hydrometer to compare results to.

[ElmoC]

Can't hurt to have a second refractometer/hydrometer to compare results to.

 

You would need three to know. If the two are off, which one is correct?

[ps2cho]

Maybe 2 refractometers, then send in for results at 2 separate labs...I'd say then you should be good.