another question......

[Ruday]

Okay ever time I add salt to my tank it reads right where I want it and then after a little while it goes back down.
to nothing it reads just fine for awhile but I added salt yesterday and it was fine I just checked it again alittle while ago and thing keeps reading none I have two different hydrometer I use one that stay in there and the other I just use from time to time to get a second opinion. I use instan ocean.
can my salt go bad and not do the job?

[StormySkiez]

I'm having the same problem with my instant ocean hydrometer after a few weeks of use. I soaked it in vinager like the package says to do to clean it to no avail. I get different readings. My tap water tested .004 to 0. IMO the salt is not going bad. My marine salt is fresh. I use instant ocean also. I think it is the hydrometers not reading properly. Anyone else have this happen?

[Agnate]

Sometimes you can get a series of very tiny bubbles sticking to the arm of the hydrometer, which can cause misreadings, especially if your tank is lower-end brackish.

My solution was to get a refractometer, as it's a lot less hassle, less mess, and better accuracy.

[crazedpuffer]

I don't have a problem with my hydrometer (Instant Ocean)
You have to fill it up slowly to get accurate results, when I used to just dip it in the tank and read it the results would often be way off.
Also if you test it right after a water change the results can fluctuate a bit too.

[Idontknow]

You are probably already doing this, but just in case...you also need to rinse it out with fresh water before and after use.