Refactometer, what to trust?

[Dburr1014]

I calibrate mine before every use. And will have sudden drifts sometimes. But my salt as per instruction also only mixes to 1.021

But you can still mix the salt to what you want. Never, never trust the instructions on the box to mix it.

 

[fullinfusion]

Using distilled water is the wrong way to calibrate.
I covered this in post #6. ^^^^^^^

Post #6 you say RODI not distilled. My manual also suggests to use distilled to check calibration.

I took mine down to the local fish shop and checked it against his really expensive one. They both read the same so really what else is there to say except, he spent $200 on his and I spent like $28 for mine. It just works and really when you look at an $80 and a $25 one they are the same. Same markings, same sights... Someone is making a lot of money off ppl these days.

 

[Justdrew]

Post #6 you say RODI not distilled. My manual also suggests to use distilled to check calibration.

I took mine down to the local fish shop and checked it against his really expensive one. They both read the same so really what else is there to say except, he spent $200 on his and I spent like $28 for mine. It just works and really when you look at an $80 and a $25 one they are the same. Same markings, same sights... Someone is making a lot of money off ppl these days.

You shouldn't be calibrating to zero. The measurement will be off when using the tank water. Calibrate with standard as close to the sample as you can.

 

[fullinfusion]

I calibrate mine before every use. And will have sudden drifts sometimes. But my salt as per instruction also only mixes to 1.021

Sudden drifts imho is user error, I dont mean to say its anyone's fault, but when you wipe down the lens are you also cleaning the top flap with a clean damp cloth? the flipper is porse and just giving it a quick rub you'll be leaving trace amounts of salt behind.. I know, I've done it myself. The best way to really check it is to use as little of water as you need and even give the top a light press to squeeze out any excess water. Everyone has an opinion on things. Thats my opinion. Last night I was mixing up some water and I got one reading of 1.026 and just before changing water I checked again and it was like 1.030 lol.. Out came the distilled water and it read off zero, I cleaned the flipper with normal water and guess what! Yup you got it, it was @1.026 so in it went

 

[fullinfusion]

You shouldn't be calibrating to zero. The measurement will be off when using the tank water. Calibrate with standard as close to the sample as you can.

?

 

[Justdrew]

?

That is what dburr is referring to in post 6. Calibrating to zero is not the best way to calibrate a refractometer.

 

[fullinfusion]

That is what dburr is referring to in post 6. Calibrating to zero is not the best way to calibrate a refractometer.

sounds good.

 

[mike550]

@MarcosTacos it looks like the calibration fluid you bought is for electronic salinity meters that are based on conductivity. That’s what American Pinpoint sells. Their solution won’t work on a refractometer.

 

[Derrick0580]

Get a small scale, add a bottle, zero it out. Add 3.65 grams of regular table sale then add enough rodi to make it an even 100 grams. This will be a perfect 35 ppt solution. I have tried a couple different calibration solutions and they have never been correct.

 

[Dburr1014]

Post #6 you say RODI not distilled. My manual also suggests to use distilled to check calibration.

I took mine down to the local fish shop and checked it against his really expensive one. They both read the same so really what else is there to say except, he spent $200 on his and I spent like $28 for mine. It just works and really when you look at an $80 and a $25 one they are the same. Same markings, same sights... Someone is making a lot of money off ppl these days.

Give this a read. It explains why calibrating to zero isn't the best idea. The slope could be off and you wouldn't even know it.

https://reefkeeping.com/issues/2004-06/rhf/index.php