Hydrometer salinity test

[mantis keeper]

Is a cheap glass floating hydrometer that comes with a thermometer accurate?

 

[Mr. Mojo Rising]

Could you post a picture? Someone might have experience with that specific tool.

My first thought is that I am skeptical to trust anything cheap... of all the money you will spend on this hobby, what is an extra $20 for something reputable that you can trust.

 

[Fish Fan]

If you've not yet purchased one, the Tropic Marin hydrometer is a popular choice:
https://www.bulkreefsupply.com/high...dUjyboE6llHhYQwVvhS_VbM2fhGbnilzLqrC2LgYycKMX

 

[mantis keeper]

Could you post a picture? Someone might have experience with that specific tool.

My first thought is that I am skeptical to trust anything cheap... of all the money you will spend on this hobby, what is an extra $20 for something reputable that you can trust.

https://share.google/FUZxBeVZUlW9Zl8Ag

I currently dont have the hydrometer but im planing to buy one

 

[Fish Fan]

https://share.google/FUZxBeVZUlW9Zl8Ag

I currently dont have the hydrometer but im planing to buy one

If you're not going to purchase the Tropic Marin, or another high-quality hydrometer, I'd suggest that you look for a decent refractometer, which are much more popular for reefkeeping than hydrometers.

 

[EnterName]

[...] refractometer, which are much more popular for reefkeeping than hydrometers.

Which I will never understand... sure the sample is small, but:

• they need calibration and getting good calibration solutions is so difficult Randy recommends creating your own,
• you have to trust their ATC which is arguably not better than needing to trust an in-built thermometer
• a few droplets change temperature fast so you will probably never read the sample at the calibration temperature where these devices work best

I say hydrometer > refractometer

 

[EnterName]

https://share.google/FUZxBeVZUlW9Zl8Ag

I currently dont have the hydrometer but im planing to buy one

That hydrometer doesn't specify the calibration temperature does it? Without knowing it's calibration temperature you won't know how to adjust for temperature.

These things should come with very clear instructions that tell you what is the actual calibration temperature and how to adjust for temperature differences.

I would go with the Tropic Marin hydrometer.

 

[PhishEDELIC]

I use to work for supermarkets that have lobster tanks. We used the cheap hydrometers with the paper rolled up measurements inside and they are not accurate. The paper can move up and down rendering it useless.

 

[Fish Fan]

I use to work for supermarkets that have lobster tanks. We used the cheap hydrometers with the paper rolled up measurements inside and they are not accurate. The paper can move up and down rendering it useless.

Yes this! A cheap hydrometer is only as good as the person that placed that thin piece of cardboard in just the right place

 

[Euphylliaphyle]

Is a cheap glass floating hydrometer that comes with a thermometer accurate?

and how to adjust for temperature differences.

+1 for Tropic Marin precision hydrometer. While you are at it, make certain you have a decent way to measure temperature! This does not need to be expensive, and perfect accuracy is not what is important. You need repeatability, since stability in temp and more so salinty are what is important. I use these (I have a few, and they all agree within 0.1°F):

https://www.lowes.com/pd/ThermoPro-TP01HW-Digital-Probe-Meat-Thermometer/5013718935
Hard to beat for $11.

 

[exnisstech]

I use a TM hydrometer then use water measured with that to calibrate my refractometers and verify my pinpoint. The hydrometer is my most trusted tool that I own. That and a plastic 500ml cylinder make it easy peasy. I have a controller for heat in my mixing brute and just bring it up to 77 degrees so I don't have to worry about calculating the temp compensation.

PS I think an accurate tool to measure salinty is the most important tool needed. If salinty is off many other parameters can be off as well.

 

[mantis keeper]

Is a cheap glass floating hydrometer that comes with a thermometer accurate?

should i buy hydrometer that is cheap but without the thermometer?

 

[Randy Holmes-Farley Verified Community Expert]

should i buy hydrometer that is cheap but without the thermometer?

A tropic Marin is a good bet. Small
Floating hydrometers can have a small and hard to discern scale on them.

But whatever you get,,you can test it in an appropriate diy standard.

 

[BryanM]

I highly recommend the tropic marin hydrometer as well. It is foolproof and adds peace of mind.