Big tip! Calibrate those swing arm hydrometers!

[castor]

I know I've seen a lot of people just say don't use the plastic swing arm type, get a refractometer which I agree with, but for those of you like me that either haven't gotten around to it or are low on cash for now, do this!

I have a Deep 6 swing arm type and finally calibrated it against a refractometer at our last MAS meeting.

His water read - 1.022
mine read it at - 1.018!

that's .004 of difference and that's pretty big! :eek1:

I was thinking I was keeping mine at 1.026, but it is actually been at 1.030!!!!

In the process of slowly lowering the salinity.

From reading around it seems the Deep 6 almost always read high and usually by about .003-.004 which mine did.

Now, people will tell you that because of this they are worthless, but I somewhat disagree. They ARE very percise in that they will give you very close the same reading on the same water 100 times in a row, what they aren't is accurate. Though they will give you the same reading, that reading might be .004 off from the true salinity.

To solve that, calibrate them! If you figure out how far from the right reading they are, you can then just add subract that much from your readings and have the right reading.

You can do what I did, have somebody test water A with a good refractometer and then you test same water A with yours, note and remeber difference + - however much.

Another thing you can do is follow the calibration methods here - http://reefkeeping.com/issues/2004-06/rhf/index.htm

Thought I would post this for the new guys (and gals) out there to help you out some. I really do recomend to anybody with a swing arm type that hasn't calibrated it to do so and do so soon!

[Jaffa]

Yup. I put mine up against a refractometer and if it reads 1.026, my Deep 6 reads 1.025.

[thrlride]

Good suggestion.

[reverai]

Mine reads the same as my refractometer....

Steve

[frybaby]

Brillant!! Thanks for the info...now all I need to do is eat a big bag of doritos with that bottle of coke! :LOL:

[castor]

Not sure about the sarcasm there what the heck the dorito and coke comment ment or had to do with anything at all....

I just posted the info/suggestion after finding how far mine was off. Yes, this may be 'common' knowlegde or whatever to most on here, but I posted this in the New to the Hobby forum, where some just getting into things might not realize they could be that much off and what to do about it. Only meaning to help even if it does seem elementary to some.

[saltydoc]

Castor,
We newbies appreciate the info - any and all info- we get on RC. Don't let one off comment make you think otherwise. I for one am using a swing arm and appreciate you passing on your experiences with them.

Thanks!

[castor]

Wait.... after rereading and thinking about it, now not sure about the sarcasm. Did you mean about the coke to use the two liter to do the calibration in the article?

If you weren't being sarcastic, I am sorry, took it wrong, been a really bad day and I need to remind myself not to post on days like this. :D ;)

If it was sarcam though, well.....;)

[theduckster]

i am sure he was referring to the 2 liter bottle in the article

[frybaby]

Cator, I have been called sarcastic before, but I really was thankfull for the info you gave! Sometimes jokes are the last thing needed on days like this. Sorry for the misunderstanding! :)

[castor]

Frybaby, really sorry about the misunderstanding. It can be hard to tell sometimes what the tone of what somebody meant online. I really hope their aren't any hard feelings. :)

[frybaby]

No worries mate! Keep up the good work!

[Hawkdl2]

Dont' forget that hydrometer accuracy is temperature dependant. Make sure you know the tmep of the water and air that at the time you calibrated it. Also, hydrometers can be unreliable due to the small bubbles that can form around the swing arm.

Larry

[castor]

Good tip(s) Larry,

I always make sure to knock all the bubbles off the arm when taking a measurement and if they won't come off I use a little trick where I stick one of those droppers you get with test kits down in there and use it to blow the bubbles off.

Also, remember to rinse with tap or R/O water after each use, and about once a month I have soaked mine in diffused vinegar for about 12 hours to completely clean any deposits off.

Hehe, another tip, just get a refractometer, lol. :D (been telling that to myself for two months and still have yet to though....:o )

[SDRotary619]

Mine was .002 off as well compared to my refractometer and it was a deep 6. It is sooo much better to have a refractometer. It is so easy to use and is vital. I waited too long to get the one I have.

[Reefmaniac1]

Another piece of info: Most hydrometers are callibrated for accuracy at 76 degrees F. If your water is not precicely 76, then it is going to be even further off the mark.

[yoyoyoo123]

why not just suck it up and buy a refractometer???

[Reefmaniac1]

It's one of the best $35 I ever spent on equipment.

[majesticangelfish]

Thanks for the info- i'll be sure to calibrate my deep 6 hydrometer.

Cheers Josh:D:thumbsup:

[wasp]

Originally posted by castor
Not sure about the sarcasm there what the heck the dorito and coke comment ment or had to do with anything at all....

I just posted the info/suggestion after finding how far mine was off. Yes, this may be 'common' knowlegde or whatever to most on here, but I posted this in the New to the Hobby forum, where some just getting into things might not realize they could be that much off and what to do about it. Only meaning to help even if it does seem elementary to some.

Well it might seem elementary, but I've been surprised in the past to see threads here with people getting totally upset because their hydrometer was out by some amount, when all they got to do is calibrate it.
May seem elementary, but I know there's a lot of people just never thought of it. So they go and by a refractometer. ( Which also should be calibrated :) )