Dont trust your hydrometer

Well .. I just bought a refractometer and found out that my SG is at 1.020  ... my hydrometer was telling me that it was 1.024 ...  ...

Edited by thebutler4 - June 09 2006 at 10:14pm

I had a hydrometer that was reading 1.022, but when I bought a refractometer, I found that my tank was at 1.030!    Yep, they can be off.  I do think that they are consistent, though.

I test for that rarely.  Maybee once a month.  I just always make sure that when i do water changes, I take out 5 gallons and put 5 gallons with five 1/2 cups of salt.  The key is.  To test your water change water and with that ratio, you should be @ 1.024.  And i know if it is off I go have it calibrated or replace it with another $10 unit.  I kinda stay away from the $100 test units Hope this helps.  Could save you money in the long run.

I think that after finding a hydrometer to be off that much that I want the peace of mind a refractometer gives.  However, refractometers need to be calibrated every so often.  I think Mark P. has a link to a reefkeeping.com article about calibrating hydrometers and refractometers.

Make sure your refractometer is calibrated.  If it just came in the mail there is a good possibility that is could be way off.

Steve, I thought we calibrated your Hydrometer when I was there helping with your move? Anyway, it's very odd that the Hydrometer was reading high. Typically, because of calcium deposits on the needle, they read low. That is - the reading shows 1.024 when the actual salinity is more like 1.026.

 

If after calibrating the Refractometer, the salinity in the tank is indeed low. There is no need to be . It doesn't matter one bit that your salinity was 1.020. If you see any difference in the tank when you raise it gradually over a day to 1.024, I'll be very surprised.

 

Okay, since a Refractometer needs to be calibrated and a Hydrometer needs to be calibrated, and by doing so, each one is accurate, why spend $60+ when $10 will do?

Ahh, that explains why they call you Mr. Salty Fingers.

 

Also, the residue of salt on the window of the refractometer from a test made a half hour or more previous, always causes the next reading to be ~.005 higher, so at work, rather than do a second finger drip, I simply adjust my reported number down by that amount. After all, it's the general range of 1.022 to 1.026 we are shooting for, not an exact number.

 

Gadgets are cool. I'm surprised that Jon hasn't made a DIY refractometer.

I bought my refractometer for $45 on special.  Great deal.  Yeah, the $10 hydrometer will work, but be careful to never drop it- I think that's what happened to mine.

I had a friend trust his hydrometer and lost everything in his tank except for fishes.  This included a frogspawn the size of a basketball.

Okay so I think you guys are all crazy.  I think hydrometers are more accurate than refractometers.  I'm testing it...