Glass Hydrometer?

[corrado007]

I understand from all of the posts out there that a refractometer is better but I was wondering if anyone had any experience with and feedback on those glass hydrometers. I've never tried one and was just wondering how accurate they are and why I haven't heard of anyone using them.

[DrHank]

I've been using mine without problems since the early 70's. It's never given me any problems. I've also got a swing arm. I use the swing arm to get close and the bulb hydrometer to be sure.

[DrHank]

As far as accuracy, mine is off by .0003 to .0005 consistantly at 80 degrees. Since salinity changes somewhat daily on the reef, I doubt that it's anything to worry about.

[reefer3]

I have read there very accerate and so I bought one but mine never did work right it is way off so now its new home is under the stand.

[mps9506]

These are generally accurate, however to use properly you want to take a tube of water out of the tank and place this in there to read.
It just takes a little longer to use and read compared to a refractometer. Also most refractometers have ATC, whereas these are calibrated at a specific temp.

[DrHank]

Absolutely correct Mike. You might also point out that a properly calibrated refractometer makes it much easier to adjust a QT for hyposalinity among other things. My bulb hydrometer is calibrated at 75 degrees. That's why there is always an error when determining SG at 80 degrees.

I've just been doing what I've been doing for so long that I'm somewhat set in my ways. Fortunately, I did give up metal framed slate bottom tanks a few years back. I do remember starting the cycle with a handful of soil from a potted plant and pushing a dead damsel under the crushed coral to push the cycle. How many of you folks can say the same?

[corrado007]

Originally Posted by DrHank

I've just been doing what I've been doing for so long that I'm somewhat set in my ways. Fortunately, I did give up metal framed slate bottom tanks a few years back. I do remember starting the cycle with a handful of soil from a potted plant and pushing a dead damsel under the crushed coral to push the cycle. How many of you folks can say the same?

I know I certainly can't say the same. Thanks for your input on the bulb hydrometer. I wonder why they don't make one that is caibrated to 80 degrees, I know I'd buy one. I guess what this all seems to boil down to is that rather than spending $25 on a bulb hydrometer which works fairly well but is a bit out-dated, one should simply fork out an extra $25 and buy a refractometer. Thanks to everyone who shared their knowledge on the topic.

[DrHank]

The error is so small in a good bulb hydrometer that it's insignificant but why not invest a bit more and get a good refractometer. I think that you will be happier with it in the long run.

[corrado007]

Originally Posted by DrHank

The error is so small in a good bulb hydrometer that it's insignificant but why not invest a bit more and get a good refractometer. I think that you will be happier with it in the long run.

I agree entirely, that's the plan. I've never used a refractometer but understand that they are fairly easy to use. Are they easy to calibrate as well and how often do they need to be calibrated?

[framerguy]

They're extremely easy. I check mine once a month but haven't had to callibrate for 3. Callibration is a snap, the unit comes with it's own screwdriver. Put two drops of test water on the glass and look through the lense, couldn't be easier. It really is the way to go. That's my 2 cents-
_______________________
Greg

[tbittner]

I agree, calibration only takes a minute. Mine has a thumb screw you turn to align it with distilled water then you lock it in place with another thumb screw. Only takes two drops but I had to buy a full gallon. lol... I've only had it for a couple/three weeks and it's still right on. Checking salinity is a breeze with it.

[corrado007]

Great, so calibrating is as easy as a few drops of distilled water and a screw adjustment once a month or so. I'm sure my wife will be thrilled to hear that I'll be buying something new for the aquarium again. The other day she found a receipt for $1,700 and looked at me all crazy thinking I bought out the LFS until I quickly explained that it was my college tuition for fall.

[corrado007]

I actually found a bulb hydrometer for $6 at the LFS yesterday so I picked it up. It's a great little thing to throw in the sump just to keep an eye on the approximate SG. It's a bit hard to get an exact reading because the scale is fairly crude on the one I bought and water movement makes it a bit more difficult to read also but at least it should remain fairly accurate unlike the 4 plastic swing arm hydrometers I have. With 4 swing arms and a bulb hydrometer I could have already bought a refractometer. Oh well, that's next.

[Scooterman]

I use the tropic Marian hydrometer, calibrated at 77 degrees F, I have a little chart to convert if temp is off. It is super accurate, I also have a calibrated Refract & they are both spot on, only thing as mentioned you need to use the glass in calm waters LOL otherwise it will bounce all day long!

[mps9506]

It's a great little thing to throw in the sump just to keep an eye on the approximate SG.

I don't recomend this for two reasons. First, it floats around in the sump and is prone to getting chipped or even shattering while floating around in the sump.
Second, stuff likes to grow on it, as soon as stuff starts growing on it, the hydrometer will quickly start reading wrong. While it is easy to clean, I think it is easier to leave in a plastic tube, and take out when you are ready to read the SG.