Refractometer calibration???

[thewire]

So I just picked one up and also I picked up brightwell calibration solution.

The brightwell is at 35 ppt. I have calibrated against that.

I calibrated the refractometer with the brightwell solution and then I tested it with RODI. With RODI solution, is the salinity supposed to be at 0? After calibration, the reading on RODI is below zero!

 

[Benga]

The bottle should specify, I believe that product should be set to 1.0264 so youll want to be calibrate it to that and then your RODI should read a flat zero

 

[thewire]

The bottle should specify, I believe that product should be set to 1.0264 so youll want to be calibrate it to that and then your RODI should read a flat zero

I did calibarated against that to 35ppt. When I measured the rodi, the reading drops below zero!

Possible defective item?

 

[Garf]

I did calibarated against that to 35ppt. When I measured the rodi, the reading drops below zero!

That's normal. The zero reading is wrong. As long as the 35ppt is good, you are good to go.

 

[Reef.]

The bottle can be incorrect, a few people on here have found that the case.

you can make your own if you have some good scales, they need to be capable of reading 0.01g

3.65g of table salt mixed with 96.35g of rodi water.

 

[CK00020]

I had problems recently with the brightwell solution, make your own. Mine read quite high

 

[thewire]

Yup don’t have a scale that measured that !

 

[Reef.]

Yup don’t have a scale that measured that !

$15 from Amazon.

 

[thewire]

So i tested with 2 other refractometers and both are reading 0 RODI and the Brightwell solution at 40ppt!

 

[CK00020]

That’s what my results were also, the brightwell was 40 and homemade was 35

 

[thewire]

That’s what my results were also, the brightwell was 40 and homemade was 35

Wondering if issue with Brightwell widespread?

 

[CK00020]

There have been quite a few threads on here about it lately

 

[thewire]

There have been quite a few threads on here about it lately

The question does RODI supposed to read 0 ppt using the standard refractometer? or maybe the Brightwell is correct?

 

[CK00020]

The brightwell I have isn’t correct, I have 3 ways of measure and they all read high

 

[CK00020]

search brightwell calibration in the search there are more than a few threads about it

 

[kelp47]

If you're worried, you might still get another calibration solution, BUT you should not be concerned that RODI is not exactly zero. The whole point of a calibration fluid of 35 is to have something in the range of what you need to measure for more accurate results. Otherwise, you would just drop RODI on your refractometer and set zero. Calibration solution would be pointless in that case. Other tools are calibrated the same way. PH probes, hygrometer, etc.

 

[MCWL]

Dont feel crazy. I calibrated mine using calibration fluid from my Trident. But afterwards I compared the rodi water. And it was below 0 also. I read somewhere that calibrating with rodi water is not a good way to calibrate.. That may be correct.

 

[DarkReefer]

My LFS told me to calibrate just using distilled water (not the RODI stuff).
Haven't tried to calibrate yet, might give it a go today as I'm on day 1 of my cycle so I'll start taking some notes etc.

 

[Reef.]

My LFS told me to calibrate just using distilled water (not the RODI stuff).
Haven't tried to calibrate yet, might give it a go today as I'm on day 1 of my cycle so I'll start taking some notes etc.

distilled and rodi are essentially the same thing, just different ways to remove impurities from water.

Use rodi or distilled and also worth making your your calibration fluid 3.65g of table salt mixed in 96.35 of rodi water, you need 0.01g scales, $20 from Amazon.

 

[ryshark]

I have 3-different types of solutions right now and they all read different, Brightwell being the highest. I’m not completely sure which one is correct. When I raised my salt to match 34 according to Brightwell, it started doing better.

With my refractometer calibrated with Brightwell at 35ppt. Then the others show
AquaCraft at 32/33
BRS at 30

I have a digital scale, but doesn’t read down to .01, I think I’m going to buy one that does.