refractometer drifting

[chris&barb]

about two weeks ago i dropped my refractometer into our salt water storage container. pulled it right out and took it apart as far as i could, dried it out on top of the AC vent for a few hours but it back together and recalibrated it with Randys calibration standard. a week later i thought it was reading a little high so i made another standard, it had drifted from 35ppt to 40ppt, a week later the exact same thing. what is causing this? is this thing toast now?

also when using a glass hydrometer the reading is taken at the bottom of the meniscus correct?

 

[Scooterman]

My glass hydrometer has lines in it with colored so called safe range, I just use the water line to read it, BTW it is as close of closer than the Refract.
If you have problems with your refract you may have salt corrosion in the unit, the best thing you could of done after dipping in salt would be a rinse on ro/di then air dry it outside all open so the humidity can evaporate off. My Pinpoint temp. controller fell into salt & I basically did the same things, any parts I didn't rinse in Pure RO/DI rusted but the unit still works.

 

[chris&barb]

i cant remember if i rinsed it in ro i know the glass hydrometers are good but we do so many SG tests per day that they are a pain.

 

[Scooterman]

Why do you have to test so much per day?

 

[chris&barb]

three clownfish larva tanks, 3 rotifer cultures, 25% water changes on all of these a day so we are constantly making new water at different SG's.

i just found a Milwaukee conductivity tester i had storied away, anyone ever use one?

 

[Scooterman]

Only person I know would be DonW, may need to shoot him a PM, I thought those were used for testing water quality as in the amount of conductive ions or conductivity of a liquid, not sure how well it would work for getting salinity at 35ppt but I have seen nice TDS/Conductivity meters at Cole-palmer or the filter guys. If your testing that much & knowing saltwater & electronics doesn't work, I'd get another Refractometer, sorta sucks but If your getting irregular drifts in your refract then this is your best option IMO

 

[Boomer]

Only person I know would be DonW

Oh come on now I have broken more of these than Don has seen :lol: I have a $500.00 conductvity meter, full scale to seawater.

Chris

I would agree with Scoot the refract has salts which is changing the RI of the refract.

Milwaukee conductivity tester

Not even close it would have to go up 40,000 ppm. Testers are only for FW. You need a conductivty meter that goes very high in uS/mS or TDS. PinPoint sells a Salinity meter that does this, where the conductivity is converted to salinity in ppt. Condcutivity is the ref std in oceanography and not density, Sg or refraction.

Scoot, I'm now going to make your head hurt..................a lot

Using Conductivity to Measure Salinity
http://www.aquariumfish.com/aquariumfish/detail.aspx?aid=1804

What is TDS?
http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.htm

Now for the really big headache.

PSS (Practical Salinity Scale)
http://oceanworld.tamu.edu/resources/ocng_textbook/chapter06/chapter06_01.htm

 

[chris&barb]

I would agree with Scoot the refract has salts which is changing the RI of the refract.

ok, so is the salt rusting something inside or are you saying salt residue inside is changing the refractive index? if its the later i should be able to rinse it out good, and it should work right? i still havent gotten off of KP from my last blunder so i hope it can still be used

 

[Scooterman]

I knew that you have & used them Boomer but was thinking for reef use Don uses his for that purpose I also had some idea that the conductivity meters were used in our hobby but wasn't sure how it was done or realized that is the real standard so I left that part wide open, I figured you would correct me:shock: Sure glad I have enough electrical schooling to even understand some of that! The first article by Randy was probably enough for me, I'll attempt the other two tonight If my tiny brain can handle it, that last one sorta look Chinese to me.

Few questions, that Milwaukee is not scaled enough for a SW reef correct & getting a conductivity meter of a higher range to get a conductivity that can be converted to a sg range that would be practical for a reef would be very costly, so we go to the Refract. for a more practical way of do it correct?

Last, Chris I don't know if the damage has been done, once the unit hits saltwater & then air the destructive process begins, don't know if you can save it.

 

[Boomer]

C & B

Yes the scale is more than likely changing the RI or the salt residue is not give the proper fit when out back together. You could try to take it apart, rinse the parts well in RO/DI water, let it air dry and then try it again. More than likely it is BO and will not work right ever.

Scoot

Few questions

Yes, that is all correct. However, there is no such thing as a table that is accurate, that I have seen, that is accurate to convert uS/mS to Sg. But there are on-line calculators to convert uS/mS to Salinity. You could then convert that to Sg. You CAN NOT take a value in uS/mS an x by some number and get Salinity, TDS or Sg, accept for a very narrow range, as the conversion factor is a function of a nonlinear equation through out the range of conductivity uS/mS to TDS/S. For **our range only** of 1.024-1.027. Then, mS to SG is ~ 0.5, close enough. Meaning, 0.5 x mS = Sg. Example 0.5 x 53mS (reading) = 2.65. Move the decimal .0265 and add 1.00 = 1.0265 Sg.

The Conductivity to Salinity Calculator
http://gaea.es.flinders.edu.au/~mattom/Utilities/salcon.html

This Pinpoint Table of mS--> S --> Sg is also close enough but is off a tad
http://www.americanmarineusa.com/salinityconversion.html

How much is a meter.

For one that has all the scales, i.e., uS, mS, TDS and S is (cheapest ) ~ $560 and with just uS/mS for seawater $500. The meter must have a range up to 100mS. So, that means that for most only the Pinpoint @ ~ $150 and the is pretty good and it measures conductivity as S.

 

[chris&barb]

alrighty, thanks everyone. looks like im scrubbing potatoes for a few more months

 

[DonW]

I knew that you have & used them Boomer but was thinking for reef use Don uses his for that purpose

I gave up on all the typical reef keeping electronics. The pinpoint salinity meters I own have a mind of their own. Every ph meter Ive had constantly needed something either a battery, probe or calibration. Just wasnt worth the effort and was taking the fun out of the hobby. I just have two refract's and dont care about ph. I have a 5 gallon bucket full of assorted meters and probes all collecting dust.
I will never buy another piece of electronics made for this hobby. They just dont hold up or are made so cheap so that they are affordable to hobbiest.
I'd just buy a new refract or two and call it good or good enough anyways.

Don

 

[Scooterman]

I even get crappy results with my pinpoint temp. probes, even if they are cleaned & side by side they never stay the same but get close at times. I've junked lots of useless hobby toys, I may be a bad influence on certain things as far as that goes

 

[DonW]

I even get crappy results with my pinpoint temp. probes, even if they are cleaned & side by side they never stay the same but get close at times. I've junked lots of useless hobby toys, I may be a bad influence on certain things as far as that goes

I think the only electronic temp probes I would trust is the one connected to my rancos. Of course they are not really made for aquariums but they are a affordable reliable option.

Don

 

[Boomer]

I agree on the refract and even just a good pH test kit, like a SeaTest/FasTest. Electronic monitoring is also a pain in the behind. When it comes to hobby grade electronics you get what you pay for. I have never owned/bought a hobby grade electronics. I use to have boxes fulll of Hanna crap. Almost all electronics in this hobby are cheap and most are made in China, as are almost 99 % of all refracts in this hobby.