Floating Needle - Specific Gravity testers

[Lurshy]

I have a Corallife 'deep-6' specific gravity tester. What are folks experience with these types of tools? Overheard two workers at the LFS dissing them, but not wanting them to sell me anything, I did not join-in in the conversation. It seems to give me consistant results, though I sometimes need to bang off bubbles on the needle. I generally repeat the test a couple of times to make certain I am getting consistant results.

 

[AgentSPS]

I have always used this kind of specific gravity tester. It is generally accurate enough for you to rely on its readings. I am not convinced that salinity is very crucial for reef tanks...Salinity varies from hour to hour in the shallow reefs where most of our coral is from. I did just purchase my first refractometer off the power buy section of this site. I have yet to use it but it seems sorta complicated. For a lazy reefer like myself...I dunno how long this will last :wink:

 

[Anonymous]

They are somewhat acurate. But a refractometer is best. The problems with swing arms are that they need the bubbles removed, some are calibrated for certain temps, some are just plain old defective. I have both the Deep Six and one of the other swing arm type(forget who makes it) and they both regester the same readings, even at different temps. So, I would say they are somewhat accurate. When compared to a refractometer they were pretty good(as long as all the bubbles were removed). It also depends on how much you have to spend. Until the powerbuys here refractometers were something almost all of us put off.

Good luck

 

[randy holmes-farley]

I tested that one in this article on specific gravity. It read about 8% low low:

http://www.advancedaquarist.com/issues/ ... mistry.htm

 

[Anonymous]

Great article.

Thanks

 

[wombat1]

I bought the refractometer too. I think a good point in the article was that the hydrometers were pretty precise, whether or not they were very accurate. This means they're still good for making sure your salinity hasn't risen or dropped day to day.

 

[Lurshy]

Thanks for the reply's. Consensus seems to be generally ok, but I'm going to get the water tested independently so I can see if it is calibrated properly as the test seems repeatable.

 

[Mike02]

That article seem to show that the swing arm wasnt accurate. i bought one of those about a year ago. tried it out and never used it again. It was impossible to get the little bubbles off. Even if there was one very tiny bubble on the arm, it would distort the reading. So, i concluded that the best bang/buck was the standard floating hydrometer. I think Tropic Marin sells one for about $16 and is supposed to be very accurate. i have a cheaper floating hydrometer which is good enough for me. The refractometers are too expensive for the slight increase in accuracy that you get.

 

[karlas]

i have a swing arm and a floating salinity tester. the floating one is supposed to be more accurate but from what i found between the 2 is the floater reads 1 pt higher then the swing arm . so they are pretty close but if you have both it makes for a good back up

 

[Lurshy]

Thanks for the reply's. Consensus seems to be generally ok, but I'm going to get the water tested independently so I can see if it is calibrated properly as the test seems repeatable.