Refractometer Testing

[Skim]

Ok I did a few different test with my meters and thought I would post what I found. I have a Milwaukee MA887 and a Red Sea refractometer that I use for testing, I also have a Old Instant Ocean Hydrometer and glass tube hydrometer. Amazing that after all these years and the IO meter is very accurate still and the glass hydrometer is still today considered one of the most accurate meters to use but can be a pain. Anyhow I was testing with Milwaukee and was getting a reading of 1.027 and 35 psu and 36 ptt and I confirmed it with the Red Sea unit.
My room temp. is 72 to 73 and tank is 79 and went back and read about ambient temp on D&D site and Red Sea Video, and decided I would try something. I put my hand on the test area of the Milwaukee and watched the temp rise to 79 and did a retest well interesting I now I got 1.024 33 psu and 34 ppt that is quite a difference so I thought how can I try this with the Red Sea unit. What I did is watch how long roughly it took to get the temp up on the Milwaukee and then stuck the RS unit in my armpit ( make sure you have a shirt on don't want any BO juice or sweat getting onto the meter ) for about 2 min and tested bang on same as the Milwaukee. I then became confused what is the better way or accurate way of doing this, so I phoned and spoke to Jason at Milwaukee Instruments and told him of my little experiment and he told me " that doing the readings by bring the units body temp up to what the water temp is, is far more accurate and the best way to get the most accurate readings". So you may want to try this out because my tests showed quite a big difference and your 1.025 maybe a 1.022 or 1.023 with a 30 or 31 ppt.
Just something else to roll around in your head. Lol

Skim

 

[zoomster]

 

[Joshbrookkate]

I have a Milwaukee unit, too. I'm going to try this tonight. I thought the units were supposed to account for the room temp in their calculation.

 

[Skim]

They do but only a couple degrees either way, at least Red Sea states that there Video. Do you try it?

 

[Pistol]

I checked my refractometer with 1.026 calibration fluid at room temp with the meter at room temp and it reads 1.026 then I floated the fluid in my sump for 10 min and checked it again and it reads 1.026, so what do you think my actual reading is?

 

[EricTMah]

I keep my refractometer at room temperature and I always float my calibration fluid in my sump before I calibrate. Seems to work this way too as I am consistent with meter and water temps


Sony Xperia Z3

 

[Skim]

I don't know pistol what is your reading, and that's what I stated on trying is it. I spoke with companies that make these units and both said you want the meter or test area to be as close as possible to same temp as the water that is being tested. I was told that the ATC ( on any refractometer ) is only good for a couple of degrees at most, so like my situation tank is in the basement and room temp is like 72 to 73 you want to bring the temp of the test area up to what the water temp is ( mine is 79 ) and that is where you will get your most accurate reading. To this day the Glass Hydrometer is considered to be the most accurate unit for S.G readings because it floats in the sample if sample is dense it floats higher and floats lower in less dense samples. Same reason Cargo ships have to take readings and know the salinity of the waters they are traveling in advance so they know how much weight they can load, too much and they will sink.
So why don't you give that a try if your room temp is much lower then your tank, I don't know you my have your room at 78 and your tank is 78 that would fantastic but if not try putting your meter in your armpit for like 2 min to bring the test area temp up and take a reading and see what you come up with.