Does anyone have a balance, and accurate flasks?

[RichConley]

Recenty, a bunch of people on Randy's RC forum noticed that their refractometers were off, and after some research, it turns out that the ones that miscalibrate against RO/DI are pretty common.

So, basically, if you're calibrating your Refracto with RODI, its probably wrong.

http://www.reefcentral.com/forums/showthread.php?s=&threadid=967301&perpage=25&pagenumber=1

Now, Randy suggested a way to make a reference solution,
http://reefkeeping.com/issues/2006-12/rhf/index.php
"This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.)."

This solution has the same refractive index as 35ppt seawater, and can much more accurately calibrate a refractometer that using RODI.


Now, I wanted to make up some solution, but I simply dont have the equipment to accurately measure out these things. I was thinking someone could make up some reference solution and make up a liter or two, so that the club can accurately calibrate these things. It could be brought to a meeting.

Anyone wanna volunteer?

 

[this is me]

So, basically, if you're calibrating your Refracto with RODI, its probably wrong.

Great, I've been doing just that for over 3 years. Damn this hobby!

 

[~Flighty~]

What about his method where you use a 2 liter bottle? I think it is much more forgiving since is it a larger ammount.

 

[~Flighty~]

He also mentions one of the calibration standards. Those only cost about $1 don't they?

I thought the tip to let the refractometer sit foe 30 seconds or so for the temp of the fluid to equalize with the instrument was helpful too.

 

[Stimpy]

setup at MTG sounds great, I have used refractometer also but I cant zero it.
maybe this idea will help me too.

 

[RichConley]

What about his method where you use a 2 liter bottle? I think it is much more forgiving since is it a larger ammount.

Theres something in the big thread about the actual size of 2l bottles not being very consistent, and the difference being as much as 3 or 4 ppt in the final reading.

 

[OceanGuy]

Equipment

I have some graduated cylinders and Harvard Trip beam balances and also a digital scale in my science class. I'm at Day Middle School in Newtonville if you want to pop on over.

I'm going to be there on Monday and late tues afternoon after 3.30. I have parent conferences until then. I'm going in to eye surgery and will be out wed thurs and friday.

I don't know if I can make it to the Dec. meeting, but will definately be at the January one. I could bring things then if you don't get it before then.
I can also calibrate my refractometer and I will be able to see it after the surgery.

Take care,
Tom

Recenty, a bunch of people on Randy's RC forum noticed that their refractometers were off, and after some research, it turns out that the ones that miscalibrate against RO/DI are pretty common.

So, basically, if you're calibrating your Refracto with RODI, its probably wrong.

http://www.reefcentral.com/forums/showthread.php?s=&threadid=967301&perpage=25&pagenumber=1

Now, Randy suggested a way to make a reference solution,
http://reefkeeping.com/issues/2006-12/rhf/index.php
"This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.)."

This solution has the same refractive index as 35ppt seawater, and can much more accurately calibrate a refractometer that using RODI.


Now, I wanted to make up some solution, but I simply dont have the equipment to accurately measure out these things. I was thinking someone could make up some reference solution and make up a liter or two, so that the club can accurately calibrate these things. It could be brought to a meeting.

Anyone wanna volunteer?

 

[JayM]

Great, I've been doing just that for over 3 years. Damn this hobby!

1 year, but same sentiment.

How often are you supposed to be calibrating these things?

 

[Matt L.]

If people are interested, I can prepare this easily and very accurately. I can prepare perhaps 1L or so worth and provide it to the club in a plastic container. Would someone be interested in coming to pick this up in Boston?

Matt