Trust Refractometer or Hydrometer

[ajremington68]

Hey, so I broke my old hydrometer and it was a very old hammy down hydrometer. So I decided to buy a refractometer to get better results. Now, I got it and I put RO water on it and it tested at the 1.000 that it says it should, and then I put my tank water on it and it tested at 1.020 which didn't seem right. So instead of dumping a bunch of salt I went to my local Petco and got a hydrometer and tried that it has a range of 1.014-1.028, and the hammer in it is going to the surface of the water reading higher than 1.028. So, which one do I trust? Is the hydrometer I bought compatible with saltwater? From what I read they are all the same. I'm gonna post links to both the hydrometer and refractometer.
Amazon product

https://www.petco.com/shop/en/petcostore/product/fluval-sea-hydrometer-4-diameter-2156287?store_code=698&mr:device=c&mr:adType=pla_with_promotionlocal&cm_mmc=PSH%7cGGL%7cCCY%7cCCO%7cPM%7c0%7ckUMWcWiLY5b1EHQjK6kSR6%7c%7c%7c0%7c0%7c%7c%7c18145199970&gclid=CjwKCAjw38SoBhB6EiwA8EQVLr_iHEYcxgVD6pXhx_5pMQlwY27QQggXuSvQ7-JCElNa9VWafYrzVRoCTwUQAvD_BwE&gclsrc=aw.ds

 

[Propane]

What kind of hydrometer?

 

[ajremington68]

What kind of hydrometer?

I posted the link to it in the original post but this is what it is called on the website

Fluval Sea Hydrometer, 4" Diameter​

 

[Propane]

If it’s a gravity hydrometer(with a little swing arm teardrop thingy) I wouldn’t trust it. There’s a DIY refractometer calibration recipe from @Randy Holmes-Farley (i think)that you can use.

 

[Sebastiancrab]

I will only trust a refractometer. You can use distilled water to test it by the way.

 

[Propane]

I also used distilled water to calibrate my refractometer.

 

[ajremington68]

I will only trust a refractometer. You can use distilled water to test it by the way.

Tested it with distilled and RO from a unit I bought for my reef tank and both are 1.000, so should I slowly add salt to raise it from the 1.020 that it is reading?

 

[ajremington68]

If it’s a gravity hydrometer(with a little swing arm teardrop thingy) I wouldn’t trust it. There’s a DIY refractometer calibration recipe from @Randy Holmes-Farley (i think)that you can use.

It is and it's a plastic one that I read everywhere that they are dog trash, just confused about why all my fish are okay in 1.020 water, but maybe they have just adjusted to it?

 

[Propane]

Fish will usually be fine at lower salinity. Many box stores run salinity quite low to inhibit disease.

 

[ajremington68]

Do you guys think I should add salt or make the drive to my local fish store tomorrow with a sample of water and see if it matches up with what they get?

 

[Propane]

Be sure to allow the refractometer to temp adjust so your reading is accurate.

 

[EeyoreIsMySpiritAnimal]

Do you guys think I should add salt or make the drive to my local fish store tomorrow with a sample of water and see if it matches up with what they get?

Double check with the fish store.

And buy one of these (but not necessarily from brs): https://www.bulkreefsupply.com/high...Iuh_AChlJK8EDwuqzfBNXaRgx_x9QU5hoC2l4QAvD_BwE

 

[ajremington68]

Be sure to allow the refractometer to temp adjust so your reading is accurate.

I put the water in and left it for a couple of mins and same results. Just worried about trusting it and dumping salt in to raise it, and it's off and then I'm just going jump parameters a lot.

 

[EeyoreIsMySpiritAnimal]

I put the water in and left it for a couple of mins and same results. Just worried about trusting it and dumping salt in to raise it, and it's off and then I'm just going jump parameters a lot.

It sounds like whatever the true salinity is, it's been that way for a little while. Waiting until tomorrow to double check at the LFS is not going to hurt anything.

 

[ajremington68]

It sounds like whatever the true salinity is, it's been that way for a little while. Waiting until tomorrow to double check at the LFS is not going to hurt anything.

Alrighty cool beans, thanks for the help everyone!!!

 

[Thumbster]

I went down this road not too long ago and after probably spending too much time on it, ended up making my own solution.

I also found out that some refractometers aren’t linear. So if you calibrate to 1.000, it may be way off at 1.026.

I was about to order a 35ppt solution but started reading reviews and it had enough negative reviews to make me wonder.

Anyway, here’s the home made standard that Randy put out. Easy enough to make at home. I ended up buying a $10 scale off amazon to measure the ingredients which consisted of Morton’s salt and distilled water.

 

[merkmerk73]

Everyone swears by the tropic marin hydrometer which is a big giant thermometer looking thing.

It does seem to be extremely accurate.

 

[Reefkeepers Archive]

Just don't trust a hydrometer, I've made that mistake as a beginner. Refractometer has the most accurate measurements, I myself use a milwauke digital refractometer but handheld ones are just as accurate. Hydrometer often get stuck or jammed and just isn't a good tool

 

[ajremington68]

I went down this road not too long ago and after probably spending too much time on it, ended up making my own solution.

I also found out that some refractometers aren’t linear. So if you calibrate to 1.000, it may be way off at 1.026.

I was about to order a 35ppt solution but started reading reviews and it had enough negative reviews to make me wonder.

Anyway, here’s the home made standard that Randy put out. Easy enough to make at home. I ended up buying a $10 scale off amazon to measure the ingredients which consisted of Morton’s salt and distilled water.

So I made this solution by measuring everything and mixing it up and my refractometer is reading 1.016. Should I calibrate it to the 1.026 that it should be to match with the 35ppm? Also, this makes sense why the hydrometer is going above because if this is correct then the salt in my tank is running about 1.030. Not sure if anyone is up to respond to this.

 

[Ianderson80]

Hey, so I broke my old hydrometer and it was a very old hammy down hydrometer. So I decided to buy a refractometer to get better results. Now, I got it and I put RO water on it and it tested at the 1.000 that it says it should, and then I put my tank water on it and it tested at 1.020 which didn't seem right. So instead of dumping a bunch of salt I went to my local Petco and got a hydrometer and tried that it has a range of 1.014-1.028, and the hammer in it is going to the surface of the water reading higher than 1.028. So, which one do I trust? Is the hydrometer I bought compatible with saltwater? From what I read they are all the same. I'm gonna post links to both the hydrometer and refractometer.
Amazon product

https://www.petco.com/shop/en/petcostore/product/fluval-sea-hydrometer-4-diameter-2156287?store_code=698&mr:device=c&mr:adType=pla_with_promotionlocal&cm_mmc=PSH%7cGGL%7cCCY%7cCCO%7cPM%7c0%7ckUMWcWiLY5b1EHQjK6kSR6%7c%7c%7c0%7c0%7c%7c%7c18145199970&gclid=CjwKCAjw38SoBhB6EiwA8EQVLr_iHEYcxgVD6pXhx_5pMQlwY27QQggXuSvQ7-JCElNa9VWafYrzVRoCTwUQAvD_BwE&gclsrc=aw.ds

I purchased this one and was broken out of the box couldn’t see the numbers and the end piece wouldn’t fit on right. So I am sending it back