Digital Thermometer Accuracy?

[Ram_Puppy]

I have a digital thermometer that runs a probe into the tank... I am not sure quite how the probe works so I was wondering if anyone knew enough to enlighten me? What i am trying to figure out, is if the line between the probe and base, could effect the temperature reading?

For instance, if the tank was 80, and the line ran up and out of the tank past the metal halide, could that exposed surface pick up heat and alter the reporting temps?

My tank is running around 83 and 84 everyday by noon, where it seems to hold steady at that point... I am about two weeks from adding the refugium, which should give me another 30 gallons of water to disperse heat... hopefully that will help.

[brewercm]

Not familiar with the thermometer but the refugium should help bring it down a little unless you're putting more intense lighting on it than in the display. Do you have any fans running on the tank, those with a good water movement on top will also lower the temp several degrees.

[BA]

also remember witth fans comes evaporation, but it's better than a chiller,price wise

[captexas]

You should keep a regular thermometer somewhere just in case. I had one of the Big Temp digital thermometers and it worked fine for awhile, but one day I noticed it was reading 75 while my house a/c is set at 78 and my heaters on the tank at 78 as well. I took the probe out of the water and the temp on the display went down to 65! My tank was really running at about 86 degrees. I'm not sure if it was due to the coraline built up on it or if the probes just go bad overtime. Even after letting it dry out for a few days, the temp was still way off.

[Ram_Puppy]

I was only planning on putting a couple flourescent lights on the refugium, on a night time cycle, so I don't think it would have any effect other than not letting the temp drop very much during the night.

The canopy is a hex (30 gallon) i built myself, it is pretty crowded in there. There are 6 20 watt Power compacts (coralife screw ins) for 120 watts of pc (50/50 10K and actinic) pretty nice... I recently added a 10K xm 175.

I HAD a 5 inch fan blowing in the opening in the back, but since I put the remora pro up there, there is no room for it. So, this weekend I cut out a 5 inch square in the top and put in a 5 inch 12v fan, covered with a grille. On the sides, I put two fans that pull air in and shoot it upwards into the lights, there are two of these so it creates a positive air pressure inside, I can feel warm air coming out the top, and around the bottom of the canopy. When I put the refugium in, the remora will go down below on it, and tha twill open the 10 x 8 hole in the back back up, and I will put the big 12 inch fan back up in there, I have an all to well understanding that that much power in that tiny of a space will be very hot... I left a bottle of windex up ontop of the canopy and man, have you ever used warm windex? even better than normal! :)

[GaryP]

Ram,

Just a piece of advice. Don't use Windex anywhere near your tank. It has ammonia in it and the sprayer creates an aerosol that allows some of it to get in your water.

Gary

[Yancey]

If you are using a digital thermometer, it is either a thermistor or a thermocouple. I'm not sure which on is cheapest (thermistor probally), and thus in your application. But a thermistor is a semiconductor device that changes resistance as temperature changes, so you can measure the resistance of the thermistor device and get the temperature of it. A thermocouple uses a junction of two different metals which produce a voltage that varies with temperature, and again you can measure the voltage and get the temperature.

And heating up the wire the display is fine (although it may induce some error possiably), but as long as the sensor is submurged it will give you a non biased reading. Now if that reading is truely accurate is a whole nother story (but it probally is).

[GaryP]

BTW, you can get inexpensive electronic thermometers at Radio Shack. I think I paid about $8 for one there. Its basically the same thing as what I bought at an LFS for $20.

Gary

[Ram_Puppy]

thanks guys, Garyp, good advice, I have a habbit of grabbing the windex from the kitchen, spraying it onto a paper towel as I walk, and then setting it ontop of the canopy and forgetting about it as I wipe down the glass... I don't even let my wife spray it on the window nearest the tank.

This thermometer that I have is the small version of the popular models, the other one has huge numbers on it. I forget the names... I double checked it against a standard aquarium thermometer this morning, and it seems to be accurate.

[jng3]

I'm using one of these,
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3212&item=43058203 12
seems to work good at a fair price. It has an alarm to boot.

[quote="GaryP"]BTW, you can get inexpensive electronic thermometers at Radio Shack. I think I paid about $8 for one there. Its basically the same thing as what I bought at an LFS for $20.

[Richard]

Not recommending this, but I just use my finger. It has 3 measurments TOO COOL, BOUT RIGHT, and TOO WARM. I got it for free when I was born. :D

[Ram_Puppy]

lol richard... problem is, you see, your not just using your finger, your using your experience, which I am sure you have spent many years forming...