CALIBRATE your refractometer!!!

[sslak]

Ok, so I always hear "check salinity with a calibrated refractometer" and I figure, duh!, that's a no brainer. I've been doing that for years...I skipped the whole swingarm hydrometer phase and went straight for a trusted brand of refractometer. It's the best way to go, everyone knows that!

Well, for the last 4-5 months I've been struggling to keep my SPS colored up. It grows, but it's all pale and brown...the more sensative stuff was pretty bad looking.

Lately I notice my LPS and even frogspawn not looking good...ok WHAT IS UP? I'm no noob! I'm running GFO, carbon, I'm 2-part dosing. My Ca and Alk are where they belong...I have a good skimmer and I do water changes with quality salt and RO/DI that reads 0tds. I've got quality lights, with new bulbs.

So I'm having a beer, doing my water tests and I misplace my refractomter. Whatever, I'll go grab my brothers out of the box in the basementq quick. Wait a second...this batch of water I just checked was way closer to 1.026 on mine...why does this one say it's so low?

I finally find my refractometer...and I get a different reading! Uh oh.

Hrmmm. I grab the bottle of calibration fluid (yeah, I had it...just never used it). My brothers checks out at 1.024...so I tweak it a little.

Mine reads waaay low. Yikes! I better check the tank!!! :thumbdown

My reef is running at 1.020...

So, I've done a large water change using 1.031 water and I'll put some saltwater in my topoff to raise it back to 1.026

Moral of the story...learn from my noobness!
CALIBRATE CALIBRATE CALIBRATE!

Just because it's always worked fine doesn't mean it isn't drifting! I feel like an idiot. Hopefully no real harm has been done...looking forward to watching my SPS regain colors. *fingers crossed*

[BigRedSpecial]

I calibrated mine as soon as I got it, then a month later, then a few months after that... It hasn't drifted on my yet. I still calibrate it every 6 months or so to be safe.

[kawicivic]

anyone have any directions for calibrating them? I bought mine used.

[Beaun]

anyone have any directions for calibrating them? I bought mine used.

35ppt calibration solution is the best and easiest way to get accurate readings.

[sslak]

Yep, I just used 35ppt calibration fluid. You take the tiny screwdriver and twist that little screw up on top at the front of the refractometer while looking through it. You will see the blue line move up or down depending on which way you turn the screw.

[jeff@zina.com]

Yep, I just used 35ppt calibration fluid. You take the tiny screwdriver and twist that little screw up on top at the front of the refractometer while looking through it. You will see the blue line move up or down depending on which way you turn the screw.

And if yours doesn't read in PPT, match it to 1.026. Though that may still be off if yours doesn't automatically take into account the temperature.

Jeff

[sslak]

Mine reads both ways, and also does adjust per temperature. At any rate, just a reminder...it's an easy thing to overlook!

[syrinx]

I read all the time how these are the only tool thats worthy of use- yet time and time again they prove otherwise. Granted they are more accurate than a plastic swing arm hydrometer-if calibrated, But the fact remains a lab- grade glass hydrometer will never have these issues. And truth be told a plastic swing arm is at least consistantly wrong- whereas the refractometer drifts. I do use a refracto when doing multi bucket water changes and such because its quicker- but I check it with my glass hydrometer first to make sure it is calibrated. I think a lot of folks just don`t know what a real glass hydrometer is-they hear hydrometer and think of the swing arm toys I guess.

[Anemonebuff]

My swing arm has been pretty good from the get go. My refractometer and my swing arm have been the same from the start. I also calibrate my refractometer every time I use it with distilled water(almost always, sometimes RO/DI). Even still the swing arm and the refractometer are always in line. I use the swing arm as an added back up test. Later down the line the refractometer needs no changing when I use 35ppt calibration fluid. Maybe I am just lucky.

[marc49127]

I just learned the hardway about refractometers! I was using the stupid swing arm style gauge and was not having much luck with my system. So I took a water sample to pruess pet's and found out my salinity was at 1.030! So I bought a refractometer and some calibration fluid and my tank is doing alot better know.

[iwishtofish]

Salinity should be raised VERY gradually, correct?

[jeff@zina.com]

Salinity should be raised VERY gradually, correct?

Yes and no. This all depends on what's in the tank and what your goal is. Salinity will often fluctuate in a nano, for example, because evaporation is such a large percentage of the total tank quantity. Most things will also tolerate hyper salinity dips for a time. Corals can handle salinity changes pretty well, they happen in nature and, unlike fish, corals can't swim to a better area.

In general, I'd recommend not to change salinity by more than .002 per day, but in reality, it happens all the time.

Jeff