Cheap Swing Arm Hydrometers Be Damned!!

[bguile]

I purchased a swing arm hydrometer when I bout my saltwater tank back in June and I read all the directions and made sure bubbles didn't sit on the arm when measuring and rinse in FW when done...blah blah...

Well, those of you that recognize me know that I've had difficulty in the past with Xenia's in my tank. I used my equipment and test kits and found nothing to be wrong..except that I got a much higher reading on the hydrometer with the LFS water. I then proceeded to raise the SG of my tank through water changes. I wanted to do this slowly, but it seemed that the SG NEVER CHANGED!! Well, needless to say I was becoming frustrated but remembered that only bad things happen fast so figured I'd calm down and proceed cautiously.

Well, something in my head told me to buy a different hydrometer. I did. One of the floating ones and when I came home to use it...oh..the horror . After raising my SG 2 points (1.024 to 1.026, reading on the old hydrometer) over a week and a half, my new hydrometer read 1.019!! No wonder I couldn't keep my Xenia alive.

Well, the good news of this story is I caught it all early before I dropped hundreds into my new tank. I'm surprised I didn't lose everything in the tank seeing that it was probably way low SG...like 1.017 or lower! For the new folks DON'T TAKE A SWING ARM HYDROMETER'S READING AS LAW. Actually, I think I'm going to purchase a second floating one just in case until I get a refractometer. Just thought I'd share. Hope it helps someone. Chime in if you guys would like. Let me know what you all use for SG. Manufacturer, model and price if available. Thanks.

[Reefland]

Hi bguile,

You are correct and it's an important but unfortunate lesson to learn; a perfect example of you get what you pay for.

The cheaper hydrometers can be used quite successfully, it is important to get them calibrated against a refractometer though. If you compare the readings against a refractometer, you can get a better idea of the actual reading it gives you and can still be used.

[Meric]

I use this method to Calibrate my Swing Arm Hydrometer:

To produce a 3.714 weight percent sodium chloride solution (SG 1.0264), dissolve 1 teaspoon (6.20 grams) of Morton's Iodized Salt in 161 mL (11 Tablespoons) (161 g) of fresh water (making a total volume of about 163 mL after dissolution of the salt). This solution can be scaled up as desired.

You can then pour this into your Hyrometer to determin how accurate it is. It is best to use room temperature RO Water for the most accurate results.

So if you make this solution and pour it into your Hydrometer and the Hydrometer reads 1.019 then your hydrometer is reading too low and you need to compensate by adding .007 to your reading every time. If your hydrometers reads off the scale, throw it away and buy a new one

[bguile]

Thanks for the mix solution Meric, but sounds like too much work for me! Just more room for me to screw something up. It's bad enough I gotta figure out the difference between 10% and 20% pink through the top or side of a salifert Nitrate kit. It's a hobby already equivalent to balancing a spinning dinner plate on a needle without having to figure out if I meant to add .02 to the SG or .08 to the PH...or was that the other way around? I need simple, straight to the point, I can't mess it up type stuff. I had taken my water to the LFS to have them test it just to make sure the floating hyrdrometer wasn't wacko too. They used a refractometer. I thought it was pretty cool when the guy let me take a look inside....the line where the blue meets white on the scale. Now that's simple! You guys suggest any particular one? I've seen some for around $100 and some on ebay around $40. Any difference in these? If so, how much?

Then again...I've learned my lesson..no more cheap stuff. So if it costs $100 then so be it. But whats the manufacturer you all recommend?

[Meric]

More expensive but you don't need to be near a light source.

[Samper]

It helps to rinse it out after every use also.