Refractometer or Hydrometer

alicel · Mar 30, 2021

I have 16g biocube. Last week (Thursday) I did about a 15% water change. It was the first water change since adding livestock. I have (had) one oscellaris clown, one trochus snail, and a zoa frag. As I was performing my water change, all was well. About an hour after I finished, my clown went into hiding and wouldn’t eat. Fast forward to sunday night - I found it dead on the bottom of the tank. I had checked on it Sunday morning and it was still hiding but not dead. I assumed it was just stressed from the water change/tank cleaning. I have always been using a hydrometer, which shows my salinity is ideal. I ordered a refractometer Yesterday and had it overnight shipped and even after calibration I am getting a significantly different reading.
Aside from the salinity, all of my parameters are good/ideal. The snail and zoa frag are happy and healthy and are thriving well.
So my question is this - which device do you trust over the other: refractometer or hydrometer? Especially knowing that other livestock seem to be doing well. I’m truly not sure what happened to the clown to end up in death. It was very healthy and stress-free prior to me cleaning the tank.

Jekyl · Mar 30, 2021

Have you calibrated the hydrometer? I do before each use to be sure.

vetteguy53081 · Mar 30, 2021

Agree on calibration and many use RO in which I am in Disagreement. Get fluid for calibration, OR take the refractometer to LFS and ask them to calibrate/test the unit

DDenny · Mar 30, 2021

You have to calibrate the refractometer. Randy Holmes Farley has a DIY calibration solution for the refractometer that is spot on. Let me see if I can find it.

Sebastiancrab · Mar 30, 2021

Alice, I have used both and go with the refractometer as long as it is accurately calibrated.

Snoopy 67 · Mar 30, 2021

That refractometer is calibrated @ 20 degrees C, or 68 degrees giving you false readings before you start.
You need one Auto Temp. compensated, ATC.

Pistondog · Mar 30, 2021

Use both, cross check.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

DDenny · Mar 30, 2021

Here is the DIY Calibration fluid really easy to do. Mine was reading at 40ppt calibrated with distilled water like the instructions said.

DIY Salinity calibration solutions

Randy, In light of another post on calibrating a conductivity meter, I decided to give it all a shot on my own system. I read through your article on DIY salinity calibration (http://www.reefkeeping.com/issues/2004-06/rhf/) and have a few questions for my simple brain. 1. Is the Brand MORTON...

www.reef2reef.com

Reef. · Mar 30, 2021

Pistondog said:
Use both, cross check.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

Buy this and a 500ml measuring cylinder, your salinity will be perfect, just make sure the water is 25c when you test it.

OrionN · Mar 30, 2021

Very accurate salinity is NOT NEEDED. Sea animals live in a broad range of salinity. Aim for about 35 ppt, a few ppt to either side DOES NOT MATTER.
Refractometer calibrate with RO water is FINE, even with tap water is fine. Minor error introduced by temperature is fine.

Spend all the time and money to get the most acculturate salinity is useless and is a wast of time and money.

Reef. · Mar 30, 2021

OrionN said:
Very accurate salinity is NOT NEEDED. Sea animals live in a broad range of salinity. Aim for about 35 ppt, a few ppt to either side DOES NOT MATTER.
Refractometer calibrate with RO water is FINE, even with tap water is fine. Minor error introduced by temperature is fine.

Spend all the time and money to get the most acculturate salinity is useless and is a wast of time and money.

Probably not the best thread to put forward that argument when it looks like the fish died because salinity was off.

davidcalgary29 · Mar 30, 2021

Pistondog said:
Use both, cross check.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

If you can't get this, you can also try one of those mini glass hydrometers off of Amazon. I have both the Tropic Marin and Amazon cheapo version, and I've found that the ripoff tracks fairly closely with the Tropic Marin model.

Also: did you ensure that the refractometer was for salinity and not alcohol? I bought (and used) the one meant for alcohol.

ReefGeezer · Mar 30, 2021

I killed my tank by trusting a swing arm hydrometer a long time ago. A temperature compensated hydrometer or a refractometer & calibration solution is all I'd ever use.

OrionN · Mar 30, 2021

alicel said:
I have 16g biocube. Last week (Thursday) I did about a 15% water change. It was the first water change since adding livestock. I have (had) one oscellaris clown, one trochus snail, and a zoa frag. As I was performing my water change, all was well. About an hour after I finished, my clown went into hiding and wouldn’t eat. Fast forward to sunday night - I found it dead on the bottom of the tank. I had checked on it Sunday morning and it was still hiding but not dead. I assumed it was just stressed from the water change/tank cleaning. I have always been using a hydrometer, which shows my salinity is ideal. I ordered a refractometer Yesterday and had it overnight shipped and even after calibration I am getting a significantly different reading.
Aside from the salinity, all of my parameters are good/ideal. The snail and zoa frag are happy and healthy and are thriving well.
So my question is this - which device do you trust over the other: refractometer or hydrometer? Especially knowing that other livestock seem to be doing well. I’m truly not sure what happened to the clown to end up in death. It was very healthy and stress-free prior to me cleaning the tank.

davidcalgary29 said:
If you can't get this, you can also try one of those mini glass hydrometers off of Amazon. I have both the Tropic Marin and Amazon cheapo version, and I've found that the ripoff tracks fairly closely with the Tropic Marin model.

Also: did you ensure that the refractometer was for salinity and not alcohol? I bought (and used) the one meant for alcohol.

David is correct. I think the refractometer you have above is not one that is used for salt water. You need a refractometer that is for salt water, sturdy, and the calibration screw does not come loose easy or accidentally.

As is I just use the IO arm hydrometer, but this is very inconsistent, and not accurate. Still, it is enough, just take care to rinse it well between use so that salt does not build up in the joint thus cause friction and air bubble does not attach to the arm.

I do not think your fish died from salinity, unless you try to change the salinity quickly. As long as the salinity change slowly, fish have been show to live long term down to a salinity of 9ppt (in hyposalinity treatment) and up to 42+ ppt. (I got fish from reef store with salinity of 42ppt when I check )

This is only regarding fish, Inverts is another mater entirely.

Pistondog · Mar 30, 2021

Some might disagree, but when doing water changes, all you want is the new water to match the tank salinity, generally.
If the new water is close to tank temp, an uncalibrated salinity match will do.

alicel · Mar 31, 2021

Jekyl said:
Have you calibrated the hydrometer? I do before each use to be sure.

I calibrated with RO. I see where people are suggesting actual calibration fluid so I'm going to look into that.

alicel · Mar 31, 2021

vetteguy53081 said:
Agree on calibration and many use RO in which I am in Disagreement. Get fluid for calibration, OR take the refractometer to LFS and ask them to calibrate/test the unit

I'll do that..thanks!

alicel · Mar 31, 2021

DDenny said:
You have to calibrate the refractometer. Randy Holmes Farley has a DIY calibration solution for the refractometer that is spot on. Let me see if I can find it.

Thank you!

alicel · Mar 31, 2021

Elaine123 said:
Alice, I have used both and go with the refractometer as long as it is accurately calibrated.

I only calibrated using RO water so I'm going to make sure that it's accurately calibrated and stick with that moving forward. I worked at LFS for years, which closed down about two years ago, and we always used refractometers there for the accuracy.

alicel · Mar 31, 2021

OrionN said:
Very accurate salinity is NOT NEEDED. Sea animals live in a broad range of salinity. Aim for about 35 ppt, a few ppt to either side DOES NOT MATTER.
Refractometer calibrate with RO water is FINE, even with tap water is fine. Minor error introduced by temperature is fine.

Spend all the time and money to get the most acculturate salinity is useless and is a wast of time and money.

I checked with tap water once and triple checked with RO. Also triple checked the water in my tank and checked the mixed up salt water I have in a 5gal bucket. I'm going to look into a calibration fluid