Mini Hydrometer

I am looking for a mini hydrometer that I can use for small batches. I typed "mini hydrometer" in the Google search bar and salt water hydrometers came up that state they check specific gravity. Will these work?

Is there any place that sells mini hydrometers for testing beer?

I've heard rumors of a 5" hydrometer, but the links are all dead. I had a similar question a while back:

https://www.homebrewtalk.com/f11/small-hydrometers-387081/

I'd love to get my hands on something I could drop in a gallon carboy of wine and leave it in there. No luck yet. I've been pulling samples with a sanitized turkey baster and using a sanitized sample column with a standard hydrometer, then pouring the sample back in. I really don't like doing that but I haven't had any contamination problems yet. If it is still early in the ferment and it is a high gravity wine I might get lucky and be able to put my hydrometer into the carboy as it floats high, but when it attenuates down to less than 1.000, no chance.

The other alternative is a refractometer, but I make do with pulling samples carefully and using a hydrometer.

I'd go to an aquarium shop and ask how they work before I'd order sight unseen on the internet.

The few I saw seem to have 1.030 as an absolute maximum gravity (and that's probably deadly for your fish). Some have a, to our viewpoint, weird "interface" in that you fill them with water and an arrow bobs. These are rather wide and require dipping into the water and thus still taking samples. Also I figure our wort and sugars would gum up the works rather quickly.

It's a neat idea but I doubt it will work. Definitely worth some-one doing an experiment though.

1.03 wouldn't do...

I suppose taking a sample and then pouring it back in will have to do. I've been concerned about oxidation mostly. I certainly wouldn't want to dump my sample as I'm starting with 1.8-9 gals.

I just sit my hydrometer in Star San for a while and place it in my fermentor. No waste.

Yeah, for my 5 gallon batches I often just put the sanitized hydrometer right in. But sometimes I pull a sample because the sample is a nice size taste of the brew! If I do that I don't return the sample.

Get a refractometer. Only takes a drop or to for a reading.