View Full Version : Hydrometer question
SaltyDawg
07-11-2009, 06:40 PM
I have been using the coralife deep six hydrometer. I read somewhere on a different thread where Iron E said he had 3 of them and the were all off by .007. This one was recommended by the LFS and the guy told me that it was what he used. I have questioned his experience from the start but assumed he knows more than me. They dont carry refractomers and I dont want to ask him for advise. What would be the best way to check the accuracy of my hydrometer, and when I upgrade to the refractometer is one better than another or are they all relative in comparison.
Bubbles
07-11-2009, 10:23 PM
i'm not sure how hydrometers work, but for refractometers, it tells you to test some tap water and make sure it sits on .000 from there you can adjust accordingly(on my refractometer at least)
hope this helps
PhotoJohn
07-12-2009, 01:09 AM
Tap water will not work to adjust your Refractometer. You must use pure water either RO/DI or distilled. You zero it out with pure water and then take your readings.
I used a hydrometer for several years without incident. I always cleaned mine after every, and I mean every use. If using a swing arm hydrometer you must make sure there are zero and I mean zero bubbles on the swing arm.
Bubbles
07-12-2009, 01:11 AM
thanks photojohn, my stupid refractometer told me to use tap water!
Iron E
07-12-2009, 02:09 AM
Most LFS's I have been to keep their salinity low. I know of one in particular that says he always keeps the salinity at "approximately" 1.012 . He says he needs to do this because so many fish are coming in with parasites and diseases, it's the only way to keep it from being a problem. He uses a hydrometer. Which wouldn't be a problem for him because if he's off by .007 his SG would still be low! He also uses tap water and maintains it is not a problem. (Could be why his tanks all look like Sh%# and he always has dead fish floating in one or more tanks.)This is also 2 very good reasons to drip acclimate your fish and QT them. One reason for fish to die on day 1 or 2 after getting them is the sudden rise in SG. Even drip acclimating isn't slow enough. Raising salinity should be done at the rate of .001 per day. So, you would have to start with a QT at very low SG and bring it up slowly over at least a week or more. I will never buy fish at that store!
I agree that you should always use RO or distilled water to zero your refractometer.
If you have any bubbles on your hydrometers arm, it will read higher than your actual salinity.
I finally threw my hydrometers away. It's like using a matchbook cover to set the points on an old Chevy. If you're desperate, it'll get you home to your timing light.
I'm not saying you can't compensate for the inaccuracy but by the time you figure out how much you have to compensate, recalculate and dip the hydrometer (sometimes repeatedly) in the tank, tap all the bubbles off the arm, make sure it's level, blah, blah,blah....
What a PITA! It's just easier and more accurate to use a refractometer.
Tom
rayme07
07-12-2009, 03:29 AM
Is the floating Hydrometers more accurate than the swing arms? Because I have both swing arm and floating but I mostly use the floating.
Iron E
07-12-2009, 12:22 PM
IME My floating hydrometer was as inaccurate as my swing-arms. IME
The only way to be sure is test it using a refractometer.
And now that you have a refractometer, you can toss the hydrometer.
I believe a hydrometer can be a precision instrument but you won't find one for 20 bucks at your LFS.
PhotoJohn
07-12-2009, 12:51 PM
in general the floating hydrometers should be pretty accurate, but my swing arm hydrometer was accurate as well
CarmieJo
07-12-2009, 01:52 PM
I have found floating hydrometers to be accurate when used properly. They need to be used in still water, at the proper temperature and the meniscus needs to be view at eye level. A graduated cylinder works well, your aquarium will not. The plastic swing are hydrometers are not necessarily accurate but they are consistent when used and maintained properly. You do need a refractometer to check the accuracy. Maybe a different LFS could help you by comparing your hydrometer to their refractometer.
http://www.wetwebmedia.com/ca/volume_3/cav3i4/hydrometers
Advanced Aquarist's Online Magazine - Lateral Lines: Hydrometer Observations Part I (http://www.advancedaquarist.com/2006/9/lines/view?searchterm=hydrometer/Impressions.htm)
Iron E
07-12-2009, 05:51 PM
If you are going to have someone check your hydrometer for accuracy, it's a good idea to make sure they calibrate/zero the refractometer before they compare results with your hydrometer. Otherwise you could still be off. Whatever method ends up being your choice, be consistent in your testing and clean your equipment thoroughly every time you use it.
Tom
SaltyDawg
07-12-2009, 07:11 PM
I clean it with hot water every time I use it but I'm worried about the accuracy. My small frags I got a couple months ago don't seem to be growing as fast as everyone say's they should. I wonder if my salinity is to high after reading about how inaccurate they can be. I dont know anyone with a refractometer to check it with. I guess I'll have to buy one and see. I'm in Maine and this hobby isn't that big up here. I'm about a half hour from the ocean so would it help to test the sea water with my guage to see what it reads. I'm saving for a protien skimmer and buying a new meter would set that back a week or two. Which would be more important?
Iron E
07-12-2009, 07:23 PM
A decent refractometer will run $20-$40 plus shipping. One I would like to get is :
Refractometer for reading salinity Bulk Reef Supply (http://www.bulkreefsupply.com/Salt-Mixes/c122/p708/Refractometer-for-reading-salinity-w/-Free-Calibration-fluid/product_info.html)
Right now I've got a $20 one I found on ebay. I liked it because it had an external adjustment knob instead of a screw adjustment. I found I keep bumping the knob and knocking it out of adjustment. I should have gone for the better quality and skipped the "convenience".
If you have a skimmer now that is working OK, I'd pop for the meter. On the other hand if you've got a system that has been running for a while and everybody seems happy, you might be OK letting the meter wait that extra couple of weeks. It's hard for me to say, not knowing more about your situation.
Tom
CarmieJo
07-12-2009, 07:36 PM
There are many reasons why one person's frags would grow faster or slower than another's. Ca, alk, Mg, flow, nitrates, water quality, lighting, SpG, and probably myriad other parameters all would contribute to this. IMO both a refractometer and a skimmer are important but many people use a swing arm hydrometer and I would get the skimmer first.
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