Reefkeeper Lite Temperature Calibration

[redfishbluefish]

OK, so I’ve inherited this 90 gallon tank with a 40 gallon sump and the Reefkeeper Lite has been maintaining temperature for about seven months…before I inherited the tank.

So I’m scratching my head why I need to replace 2+ gallons a day in evaporation and why some on the corals aren’t looking right. I put in one of the mercury thermometers into the tank and it says the tank is about 81 degrees. I have three other mercury thermometers, and test them all, and they all say about 81 degrees. My Reefkeeper is saying it is 78 degrees.

Here’s the question. Do you need to calibrate a Reefkeeper temperature frequently? If so, how frequently do you do it? If not, might I assume mine was never calibrates? Am I the only one who feels the instructions to this piece of electronics sucks?

 

[radiata]

I only started using my ReefKeeper iTemp last week, so I can't comment on how often it needs calibration, and yes, Digital Aquatics is in need of a decent documentalist.

The quest for an accurate temperature reading is more difficult than most people think. Most thermometers claim to be accurate to +/- 1 degree centegrade (+/- 1.8 degrees Farenheit). So a 78 degree F reading on your average thermometer means that the actual reading is somewhere between 76 and 80 degrees, if you're lucky. So much for state-of-the-art.

Getting a more accurate NIST certified thermometer is probably going to cost you well over $75. I did pick up a $30 digital thermometer that can be field calibrated - using a mixture of ice and water in a specific ratio to get you to 32 degree liquid. Is that how DA does it, or do they just say "get a solution of a known temperature"?

 

[Brando457]

sorry to thread jack but when you first plugged in your RKL did your lights turn on immediately or do you need to set each outlet for their given tasks?

 

[radiata]

sorry to thread jack but when you first plugged in your RKL did your lights turn on immediately or do you need to set each outlet for their given tasks?

I believe I had to set each output first.

 

[redfishbluefish]

sorry to thread jack but when you first plugged in your RKL did your lights turn on immediately or do you need to set each outlet for their given tasks?

I can't answer this because, as I mentioned, I inherited this tank and therefore did not do the original setup.

 

[cmor1701d]

Interesting that your digital is reading lower than your mercury. I just posted the following on a heaters thread...

I'm currently waiting for an inspection at work to end so our metrology deparment can tell me whether my digital or my mercury thermometers are correct. Two digital thermometers agree with each other and two mercury thermometers agree with each other. The digitals reads 2 degrees higher than the mercurys.

So my digital controller reads 81, my digial handheld read 81.4 and my mercury thermometers read 79 (one cheap plastic and one glass long stem lab thermometer).

I should know this week which are correct (if any).

 

[redfishbluefish]

Well my story gets better. I just recently picked up a Reefkeeper 2 and calibrated the temperature of the RK 2 to the Reefkeeper Lite’s temperature. I actually did this for maybe three days straight of readjusting the calibration so that they matched. I think the last calibration I did they were both at 78.4. So both were exactly the same. That was about two weeks ago. As I sit here next to the tank, the RK Lite says 79.0 and the RK 2 says 78.2. And by the way, both probes are right next to each other. I give up!

 

[magic]

Paul

They are accurate + or - 1 degree so that's not surprising . It's frustrating! I have a AC Jr that started acting up. One step forward two back.

Bob

 

[ynotme4886]

Hmmmm interesting. I got my RKL a few weeks ago and never thought to check the accuracy of the temp probe.

Gonna hafta get out my handheld ph meter and see what it reads for temp (tells both temp and ph) and maybe BORROW the digital meat thermometer from the kitchen while the wife isnt looking to see what that says.

Will post what mine says later tonight

And yes their instruction manual sucks big time. If I hadnt had a AC jr for quite a while I never could have set this thing up with what was sent in the box.

 

[radiata]

Hmmmm interesting. I got my RKL a few weeks ago and never thought to check the accuracy of the temp probe.

Gonna hafta get out my handheld ph meter and see what it reads for temp (tells both temp and ph) and maybe BORROW the digital meat thermometer from the kitchen while the wife isnt looking to see what that says.

Will post what mine says later tonight

If you plan on using the average of the three readings, you could get a nice inaccurate average. Inexpensive thermometers are not accurate - most are +/- 1 degree C (+/- 1.8 degrees F), so your 78 degree F reading could easily be anywhere from 76 to 80. Check out this Cole-Parmer list for thermometer type accuracies: http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=TempInstRanges.htm&ID=718. Then poke around their catalog - more accuracy comes with a price.

 

[evoIX]

i would keep within the vicinity of 78degrees. if your mainly concerned with controlling temp with your rk system. why are you too worried about a 1 degree drop. if you want absolute accuracy that's fine. but the livestock in which you spent HUNDREDS of dollars on will do well versus not being in that 1-2 stable environment.

i have a rkL and happy that it keeps my temps stable at about 77-79degree temp and will cool or shutdown anything if necessary. i used two different temp readings from a handheld coralife digital and a cheap mercury temp reading. if close good if not get the median unless extremely off

 

[JRWOHLER]

I see the bigger problem is the one that Paul has with the two RK...fluctuation in temp is the problem, in particular if your Reef Computer is monitoring and adjusting the temp. I keep one cheapo thermometer and my AC Jr in the tank all the time. I had one of those garbage digital thermometers go haywire....87 was reading 76 , I figure a hanging thermometer may not be completely accurate but should be reliably inaccurate with no electronics to fail.

 

[ynotme4886]

Well I checked mine against my Hanna handheld ph temp checker thingie and found out 2 interesting bits of info.

The handheld meter says my temp is 1/2 a degree higher then the controller. I can live with that cause I do not use the controller to control my temp, just monitor it.

However the ph numbers between the 2 units was way out of whack. The ph probe on the controller is less than a week old and was calibrated when installed.

Looks like I need to dig out a packet of calibration solution tomorrow morning and see which one is screwed up.

Wanna place bets on which one it is?? I'm betting the controller.

 

[ynotme4886]

Well I was wrong....was the handheld that was outta whack. The one in the tank was off by .02

Its such a pain to calibrate the one for the RKL that I am just gonna leave it be for now