Hydrometer

I'm not exactly sure where to put this so its here. LOL

I have two floating hydrometers. For some reason they have different readings. Both have a green zone indicator. On one of them, the water line is right in the middle. On the other, the water line is barely touching the bottom of the green zone.

Which one should I "trust?" Has this occurred to anyone before.

 

My answer would be to get a refractometer. Everything I've read says hydrometers are too variable and inconsistent.

Just my opinion. Other choice would be to go to your LFS and calibrate it against their water and their reading.

M

 

Get a refractometer. They are a lot easier to read, they are more accurate and really aren't that expensive. I bought mine from marine depot for like $45 I believe.

I have experienced exactly what you are talking about. I had two hydrometers before I got my refractometer and they never read the same thing. Worst of all if I had the salinity tested at a LFS their reading was different.

 

I used a hydrometer about 3 years ago for about 3 months before I realised that it was the reason for many problems in my tank. My hydrometer was reading 1.024 but fish kept trying to jump out the tank and continually had whitespot plus corals kept dying in the end I got a refractometer and my water was actually at 1.032. IMO hydrometers are useless, they need to be calibrated against a refractometer and make sure that you rinse it with RO water otherwise salt can build up on the swing arm and put it even more out of range.

The best thing you can do is get a refractometer hopefully your tanks salinity won't be as out as mine was.

 

I would have to agree, most of us who have been in the hobby very long has switched to refractometers. There just isn't a good hydrometer unless you pay big bucks for a lab grade one.

 

Let's say you only have a mechanical Hydrometer for tonight???? What would you do?? Lay it on a flat surface or hold it up by the finger hole locations on the top of the Hydrometer???????

 

I would make up a litre of fresh seawater using RO. On the salt mix box it should say how many litres of seawater it can make e.g. 7kg makes up 210 litres (taken from my Red Sea Coral Pro tub) this means that to make up one litre you need to add (7 ÷ 210 x 1= 30) 30g of sea salt to RO should give a salinity of around 1.025. You can then try this sea water solution in your hydrometer to see how much it reads and then you can work out approximately what salinity your tank is at. This can only work if your sea salt has remained sealed as much as possible as the salt can absorb water if the tub is left open and that will mess up the weight of the salt.
Before and after you use the hydrometer make sure you rinse it with tap water to remove any residue salts. I would buy a refractometer as soon as possible. If you LFS is open, not sure on the time in your area right now, you could take a sample of tank water to get them to test it for you with a refractometer.

 

i would order the refractometer off eBay tonight.

but, seeing what you are saying. for tonight, I'd lay them flat on a surface and average them. then I'd see how off they were when my new refractometer came in the mail! ;D

 

Gee let me tell you a story i have 3 glass hydrometers and they all read the same used them for years with no trouble , bought a refractometer and it reads different after rechecking the calibration 3 times using 2 different methods, i am not sure witch one to trust and the local fish store dose not help me much because he uses a hydrometer to check his tanks.