First Time Mixing Salt with a Refractometer

[acuario]

Getting ready to soak my "dead" rock in preparation for my first tank in many years. I am trying to use a Milwaukee Seawater Refractometer (the green one - MA887) to mix up some saltwater. Battery is at 99%.
First step says to calibrate:
OK. So when I put a little DI water on the lens and hit the "ZERO" button, the display gives a "LO" reading. The manual states a LO reading means: "Sample is reading lower than the 0 standard used for meter calibration." Not sure what that really means? Do I need to use something other than DI water here? The water is covering all of the lens.
Second try:
I put a bit a few drops of Refractometer Calibration Solution by Aqua Craft Products to cover the lens. If I hit the "ZERO" button, I get a reading of 1.000 specific gravity. If I do it again and hit the "READ" button, I also get a reading of 1.000 specific gravity.
Third try:
If I calibrate with the RCS by Aqua Craft (to 1.000 ppt) and then test my first batch of saltwater, I get a "LO" reading.
Do I need more salt? I can't find any information on how to proceed if you calibrate with RCS and not DI water as some recommend? I bought this refractometer on the forums here. I'm not sure what to do next but I wish I had my old hydrometer back. Any help would be appreciated. Thanks.

 

[ericarenee]

My opinion..
many here will say i am wrong.
GET A GLASS HYDROMETER AND BE DONE WITH IT...

having a nice Kewl Gadget is fun .. But well.. When you have to test your test equipment before you can test what you bought the test equipment for.. Its time to just test with a tried and TRUE Method....

Glass Hydrometer

Just my two cents.... ok its more like 99cents worth..

 

[acuario]

Of course, Keep it Simple...
I saw another forum where they were getting the "LO" reading, it was never resolved.

 

[Breadman03]

I have a refractometer. Honestly, the bag got wet and salt fouled up the zipper. I just use my swingarm hygrometer.

 

[johnike]

I have a swingarm matched to a friends refractometer.

 

[Bent]

I have a refract that I use for beer brewing.

I used it to see how accurate my swing arms are.

The swing arms, which have spent the last 10 years in storage, were dead on.

Strange.

 

[kfisc]

It's all about calibration. Over time, even refractometers can deteriorate- coatings can chip loose inside the device, adjustment screws can corrode, etc. Swing arms can get coated with deposit, throwing them off, but cleaned up and with a known reference point, they're good to go ad infinitum.

 

[BrettDS]

I put a bit a few drops of Refractometer Calibration Solution by Aqua Craft Products to cover the lens. If I hit the "ZERO" button, I get a reading of 1.000 specific gravity. If I do it again and hit the "READ" button, I also get a reading of 1.000 specific gravity.

You can't zero it out with Refractometer Calibration solution. The solution should be 35ppt (or 1.026). I'm not sure if that device has an option to calibrate with 35ppt solution or not, but if your only option is to hit the "zero" button then you'll need to use purified water to calibrate it.

 

[Sk8r]

SKip the glass hydrometer.
To mix salt water, read the instructions.
Generally, start with ro/di. Get a measuring cup that allows you to scrape off the excess in the cup, ie, level, with a knife. In general the proportion is 1 gallon of water, 1/2 cup of salt mix. To do 30 gallons of water, put in exactly 15 cups of salt. It helps to use a container with a known measure: ask in the cooking section of a store. A multi-set of measuring cups has a measure for 1, half, 1/4. When asked for a cup, scrape it off even.
The internet will convert cups to gallons, and vice versa.
Start with that surety.

Then mix with a pump overnight. THEN measure the salinity WITH a refractometer. [Takes time to dissolve.]

If you did everything right, you will see you have 1.024 salinity, which is exactly right for a reef or invertebrates. Always. If fish-only, no invertebrates, you can go to 1.018.

 

[ericarenee]

SKip the glass hydrometer.
To mix salt water, read the instructions.
Generally, start with ro/di. Get a measuring cup that allows you to scrape off the excess in the cup, ie, level, with a knife. In general the proportion is 1 gallon of water, 1/2 cup of salt mix. To do 30 gallons of water, put in exactly 15 cups of salt. It helps to use a container with a known measure: ask in the cooking section of a store. A multi-set of measuring cups has a measure for 1, half, 1/4. When asked for a cup, scrape it off even.
The internet will convert cups to gallons, and vice versa.
Start with that surety.

Then mix with a pump overnight. THEN measure the salinity WITH a refractometer. [Takes time to dissolve.]

If you did everything right, you will see you have 1.024 salinity, which is exactly right for a reef or invertebrates. Always. If fish-only, no invertebrates, you can go to 1.018.

This assumes the salt mix is perfect And there is no compression .. I can fill my salt bin up to where the lid will not fit... Then tap on the side of the container and the get it to pack down and hold at-least another 1/2 gallon of dry mix.... So do you use loose salt mix from the top.. do you pack it down some. If so how much... if you do not pack it down how do you determine how much its packed down say half way down the bucket to how much it was on the top........

I have also seen way more bad experiences with OUT OF Calibration Refactors then glass or swing arm hydrometers that are kept in clean Working condition.......


This reminds me of the test kit debate...

 

[Sk8r]

I roll the barrel across the floor multiple times, turn it over, roll it some more before opening it.

Plus I apply a little culinary art: you generally are assumed not to 'pack' a measure hard, but to free up the substance to be measured, dip it up as it sits, easily, then trim the top off with a knife or such. Small errors in small amounts show up more. But if you note you aren't at 1.024, you just add water or salt and mix some more, using the refractometer to judge tiny adjustments. By the time you add 20 gallons of 1.025 to 80 gallons of tank at 1.024, you'll not really see much difference anyway. Long as you don't jolt the tank out of the 1.024-1.026 'pocket' , you're not going to hurt anything, and evaporation or the addition of a little freshwater will haul it into line. Most organisms tolerate a change of .002 just fine, whether up or down. More than that, not so good.

 

[vhuang168]

I use Red Sea Coral Pro and on the back of the bucket they have a chart listing weights for the amount of their salt for various salinities.

I've never gotten anything other than salinity as stated on the chart if I measure everything correctly.

On the digital refractometer the OP has, I use the same. Instructions say to calibrate with RO/DI.

 

[ericarenee]

I use Red Sea Coral Pro and on the back of the bucket they have a chart listing weights for the amount of their salt for various salinities.

I've never gotten anything other than salinity as stated on the chart if I measure everything correctly.

On the digital refractometer the OP has, I use the same. Instructions say to calibrate with RO/DI.

Kent marine is very is exactly the same . never exact... and i mix 50 gallons at once in a 55 gallon tank... not a scoop at a time...

 

[RGS2]

Then mix with a pump overnight. THEN measure the salinity WITH a refractometer. [Takes time to dissolve.]

Read the directions for your specific salt. Some like Ref Sea Coral Pro suggest only mixing 30 minutes to 2 hours, and no more than 4 hours max.