water temps - when to give up the fight!!??

[reef tank 2.0]

i'd like to add another topic that is causing stress.....water temperatures!!
I have 10 thermometers going. One being an old fashioned mercury thermometer, and the other 9, are digitals.

I have a bowl of ice water that the thermometers have been sitting in for a good 20 minutes or so.
I have watched the temps go up, down, and everything in between. i've stirred the water, let it sit, trying to get it down to 32. ends up being a few degrees off of the 32 mark. Bowl still has ice in it, and the temps rise...how on friggin earth do themps rise when sitting in ice!!!! maybe i was asleep in science class that day

here are my results, in degrees, in the 20 or so minutes.
35+/- (mercury thermometer) (lines are really small, this is an educated guess)
34.5
33.6
35.4
35.9
34.3
34.1
35.7
34.3
34.8

only two of those dang thermometers read the same. I am trying to find 4 thermometers that will all read the exact same temperature, That way i won't have to worry about water temps being different between water changes, water top offs, and normal every day living.

how do you determine which thermometer to go by? i want my temps to be consistent, but there is nothing consistent about the readings shown above.

 

[littlefoxx]

i'd like to add another topic that is causing stress.....water temperatures!!
I have 10 thermometers going. One being an old fashioned mercury thermometer, and the other 9, are digitals.

I have a bowl of ice water that the thermometers have been sitting in for a good 20 minutes or so.
I have watched the temps go up, down, and everything in between. i've stirred the water, let it sit, trying to get it down to 32. ends up being a few degrees off of the 32 mark. Bowl still has ice in it, and the temps rise...how on friggin earth do themps rise when sitting in ice!!!! maybe i was asleep in science class that day

here are my results, in degrees, in the 20 or so minutes.
35+/- (mercury thermometer) (lines are really small, this is an educated guess)
34.5
33.6
35.4
35.9
34.3
34.1
35.7
34.3
34.8

only two of those dang thermometers read the same. I am trying to find 4 thermometers that will all read the exact same temperature, That way i won't have to worry about water temps being different between water changes, water top offs, and normal every day living.

how do you determine which thermometer to go by? i want my temps to be consistent, but there is nothing consistent about the readings shown above.

To be honest I use the strips that stick to the glass for a ballpark number and my hand to gauge the temp. I can tell if the tank is too hot or too cold that way but I dont stress too much about it. I have a heat problem in the summer so I check way more then

 

[fishyjoes]

I don't think temperature matters that much.
It matters, don't get me wrong, but a half a degree isn't worth pulling your hair out for.
To get the precision you seem to want will take very expensive lab equipment.

 

[reef tank 2.0]

i guess my biggest issue, is that if i think my water temps are at 78, but in all reality they're at 85......I'd have no way of knowing for sure. I see the preferred range is 76-80. that's not a big range, especially when the thermometers are not precise.

 

[reef tank 2.0]

now that i think about it, i do have a FLUKE temperature gun that i use for work....wonder what that reads.....please hold...

that reads 30 degrees, good grief

 

[JayM]

Your biggest differential looks to be less than 2° between the lot. Considering the amount of water typically exchanged during maintenance - I don't think that's enough to be concerned about.

 

[JAS927]

A small difference is all you have between these thermometers. It’s truly not enough to worry about. Select the closest ones and call it a day. You aren’t going be 5+ degrees off at any given time if the majority are reading the same.

 

[Pistondog]

THe sensors used are cheap thermistors they give very little differential signal at low temps, they do better around room temp. Repeat your test in stirred room temp water, they will be closer together. Not very accurate, but will show temp changes.
If you are concerned about accuracy, you will have to spend a little money. Key is a good sensor, pt100 rtd is best.
Use 1 good temp reference to calibrate the others.

 

[Joekovar]

I pay more attention to my HVAC temp than anything in the tank. I've found that my temp stays within a 1-2° of what the HVAC thermostat in the room says.

I don't run a heater in the tank though.

 

[fish farmer]

To be honest I use the strips that stick to the glass for a ballpark number and my hand to gauge the temp. I can tell if the tank is too hot or too cold that way but I dont stress too much about it. I have a heat problem in the summer so I check way more then

I use one of those little floating glass thermometers that has the safe range in green...70's. I try to keep it around the top of the green.

To the OP, pick upper 70's, get some type of temp controller, if one of your thermometers is way off like 5 degrees or more, don't use that one.

I'm more concerned about temp swings from heat waves or power outages, but considering my tank went down into the upper 60's for half a day and everything lived, I don't stress as much.

 

[reef tank 2.0]

@Pistondog - I placed all the thermometers in the display tank, and the readings were certainly a lot closer together. What you said is certainly spot on......I feel more comfortable with this.......The last thermometer will NOT be used. I think I can leave the temperature as it is now. I'll adjust the water bins accordingly.

here are my results, in degrees
78-80+/- (mercury thermometer) (lines are really small, this is an educated guess)
78.3
78.2
78.4
78.9
78.9
78.4
78.6
78.4
80.2