Are these temp readings possible?

My Acu-rite is giving me temp readings that are up to 20 degrees different for 2 places that are about 20 inches apart, and with mostly open air between them. Neither the probe nor the main device is under a hide, or behind anything else that might make it a sheltered spot where I might expect such a significantly different temperature.

My tank is a 20 gallon glass tank with a screen top. A piece of styrofoam like stuff is setting on the screen and covers most of it to insulate and trap the humidity. We are using a UTH for heat. It is connected to a rheostat to enable us to fine tune the temps. We have the $12 digital Acu-rite that gives temp, humidity, and another temp from the probe. When I checked the gauge a few minutes ago, it read 90.9 warm side, and only 70.9 on the cool side! Humidity is 44%.

I know 70.9 is too cold. That isn't my question. I'm wondering if I need to figure out a way to add a little heat to the cold side preferably without totally changing my set-up and buying more stuff, or is it more likely that I have a faulty Acu-rite?

We did notice when we first installed the battery that even when we put the probe right beside the main unit, the probe consistently read about 2 degrees cooler than the main unit. We weren't terribly worried about it since I have heard that the digital gauges are accurate within 2 degrees. But now that we are getting such a big difference within the open area of a fairly small enclosure, I'm wondering if the whole thing is messed up.

Any thoughts?

It's entirely possible. My 20gal is well set up with the screen foil insulated and the temps were great during summer. Now that its cooling down, my warm side still stays between 88(at night) and 92 with the t-stat, but my cool side dropped to 74 at one point.

My suggestion: get a second UTH for the cool side, especially if you live somewhere that can get really cold, like me, on a t-stat preferably. I found that rheostats are fine for the warm end, but they can't get down far enough for the cool side even on the lowest of the low settings. The second UTH, well controlled, should keep your temps stable throughout the winter...and if you add foam insulation to the three sides of the glass (as I'm about to do), you should be good to go.

Pictures are a little bit better to assist you and answering your question. Im thinking you have the accurite to close to the vent opening....

Right now all we could do is assume this and that.

Thanks for the replies. Unfortunately, I don't have a way to put up any pics right now.

For the moment I'll go with the assumption the readings are accurate. I need to figure out a way to verify it without buying another thermometer.

The open part of the screen top IS on the cool side of the tank. I was thinking if I put it on the warm side, the heat would just go straight up & out. Should I reverse it? Maybe less heat would get to the cool side, but once it got there it would be trapped making it stabilize at a warmer temp?

I already expected to need to get a t-stat by the time winter gets here. It does get cold here, but not as cold as Denver! I just thought I was done with the spending for right now. Oh well. I guess I'll be heading out later to get a t-stat and another UTH. I assume a smaller size UTH is ok for the cool side? Or does it need to be even coverage, just kept cooler by the t-stat?

I do already have a very thin make-shift insulation on 3 sides of the tank. My plan is to get that foam poster board stuff and decorate it to make an attractive backdrop for the more permanent solution. I hoped with the mostly mild fall weather getting it done in a week or 2 would be soon enough, but maybe I should get some thicker cardboard so the temporary insulation will be more effective. Maybe I should also get something that could be put on the front of the tank at night to minimize night time drops in temp?

In the very short run, I've got a lamp I can turn on and aim where ever necessary for a few minutes at a time to raise the temp. It makes the temp jump up pretty fast, so I don't even step away, just watch the gauge. But once I've done this it drops off a lot slower.

Thanks again! I welcome any more suggestions or comments.

To verify without buying a new thermometer (although it never hurts to have a spare)....try switching sides with it. Put the unit on the warm side and the probe on the cool side...and see what kinds of readings you get.


If the room you have the tank in is around 70 degrees, then it IS likely to actually be that cool in there. UTH's are great for creating a basking spot, but they won't warm the entire enclosure...especially if it's a big, glass tank.

Try getting another dimmer switch for the lamp so you can leave it on all the time as well. (But you'll need to get a red or blue bulb so it doesn't bother the snake...or a ceramic heat emitter...which screws in like a bulb but doesn't put out any light, just heat.) Sounds like you definitely need some supplemental heat to get the overall ambient temps of the tank up closer to 80.

EDIT: One more thought about a second UTH for the "cool" side....I wouldn't. Again, it will just create a small warm spot, without actually adding any additional heat to the tank. You need something to radiate warmth and warm the whole tank up to around 80.

I wouldn't assume it's accurate. I JUST bought an Acu-rite thermometer/humidity gauge yesterday (digital one with probe), and it was reading normal temps this morning... I come home and it says the temperature is 43.9F on warm side, 39.7F on the cool side. I think I would know if it was that cold in the room! Talk about Acu-wrong. :(

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Originally Posted by icygirl

I wouldn't assume it's accurate. I JUST bought an Acu-rite thermometer/humidity gauge yesterday (digital one with probe), and it was reading normal temps this morning... I come home and it says the temperature is 43.9F on warm side, 39.7F on the cool side. I think I would know if it was that cold in the room! Talk about Acu-wrong. :(

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Just a thought did it some how get switched over to celseus ( sp ) ?

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Originally Posted by jotay

Just a thought did it some how get switched over to celseus ( sp ) ?

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Nope, it's still Fahrenheit.

I don't currently have an Acurite brand thermometer, mine's Radio Shack. But, you should be able to tell where the main unit gets its reading from by looking at it. Mine has a little "speaker grill" looking opening on the front. I can place the probe on that grill to get the inside and outside temps reading the same. You should be able to accomplish the same thing. If not, you could probably stick the whole thing in an ice chest (no ice!) or other insulated container, wait a while, and the inside and outside temps should be pretty close.

Steve

The temp difference is possible.


To maintain temps between 80 and 84 on the cool side you have several options

1# Buy an additional heat mat as well as an additional thermostat set to achieve 80-84 or
2# Have your BP in a room where the ambient temp is maintained in the low 80's with the help of a oil filled heater.

Icygirl, thank you for sharing the info about your obviously not accurate Acu-rite. I definitely hope it is malfunctioning rather than just switched to Celcius, as if those were C readings, it would translate to temps of 111F and 103.5F. Although I do give Jotay credit for thinking of that possibility; it just isn't the right answer this time. Definitely take that defective gauge back and exchange it for a new one! And that means tomorrow I'll be trying a few things to try to verify whether or not mine is accurate. I appreciate the ideas people have given for testing it.

JLC, at the risk of sounding like one of those people who asks for advice and then says "I think you are wrong, I'm going to do what I feel like doing no matter what you say"... I'd like to ask what makes you say that a UTH doesn't provide enough heat to get the ambient temperature of the entire tank high enough? When I first read your reply, I thought uh-oh, and went and took a little twist-tie to hang the probe from the screen so I was measuring the temp an inch or two from the top of the tank, rather than on the floor. After giving it an hour to make sure the temps had at least mostly stabilized again, I switched it to the other end of the tank and did the same thing. I didn't turn on the lamp at all during those couple of hours to make sure that whatever reading I was getting was being maintained by the UTH. The air temp on the warm end was 79.3, and 77.4 on the cool side. So really the only place that is significantly too cold is the floor on the cool side. Heat rises, so it isn't surprising the coldest spot is the floor where there is no UTH, and adding a UTH there sounds like the perfect solution. Am I missing something?

do you have air conditioning running in the room? If so, where is the vent in relation to the tank? Could it be blowing directly on it? Just a thought!

Steve

You could always cover both ends of the enclosure and leave your ventilation open space in the middle. :) You could also just nudge the UTH a bit move over towards the cool end...not a huge amount, just a bit sometimes is all that's needed once you deal with that open mesh that's letting out pretty much every bit of heat and humidity that makes it's way over to that cool side.

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Originally Posted by kc261

Icygirl, thank you for sharing the info about your obviously not accurate Acu-rite. I definitely hope it is malfunctioning rather than just switched to Celcius, as if those were C readings, it would translate to temps of 111F and 103.5F.

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It's definitely still in Fahrenheit. The "cool side" temp, when switched to Celsius, says around 6C (almost freezing)! I'm going to return this thing to Walmart when I get the chance.

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Originally Posted by kc261

JLC, at the risk of sounding like one of those people who asks for advice and then says "I think you are wrong, I'm going to do what I feel like doing no matter what you say"... I'd like to ask what makes you say that a UTH doesn't provide enough heat to get the ambient temperature of the entire tank high enough? When I first read your reply, I thought uh-oh, and went and took a little twist-tie to hang the probe from the screen so I was measuring the temp an inch or two from the top of the tank, rather than on the floor. After giving it an hour to make sure the temps had at least mostly stabilized again, I switched it to the other end of the tank and did the same thing. I didn't turn on the lamp at all during those couple of hours to make sure that whatever reading I was getting was being maintained by the UTH. The air temp on the warm end was 79.3, and 77.4 on the cool side. So really the only place that is significantly too cold is the floor on the cool side. Heat rises, so it isn't surprising the coldest spot is the floor where there is no UTH, and adding a UTH there sounds like the perfect solution. Am I missing something?

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No...not missing anything. I was just speaking from personal experience of trying to heat a glass tank in a cool room. Yes, heat rises...but the room was cool enough that the heat would dissipate through the glass before allowing the air inside to reach and maintain warm enough ambient temps. Maybe it'll work for you, though. Good luck with whatever methods you try. :)

The weather has been very pleasant for several days now so we haven't been running the AC. There may be some drafts in the room due to the fact that none of the doors in this house seem to fit their frame very well, but nothing as bad as AC blowing directly on or near it.

JLC, thanks for explaining about your experiences with the UTH in a glass tank. The difference here may be that the room isn't as cool as the one you had your tank in, and/or my tank is better insulated. Either way, during the winter, we let the house get pretty cool at night, so I better be prepared to prevent the temperature in the tank dropping. From the testing and experimentation I've been doing, it looks like the extra UTH will work fine in the current conditions, but may not be enough year round.

i have a 55 gal glass aquarium and use a uth hot side stays 90-93 cool side 80-82 humidity 60 63% i have a good 3/4's covered with 3 layers tinfoil shine side down 3 layer ducktape seems to be working for me.
i would think your guage is out

A Radiant Heat Panal solved my problem as far as bringing up the ambient temps but that would be a task to use with a glass tank setup. I have noticed with it approaching fall that I have some tweaking to do from last winter. The other night it dropped to the 40's and I woke up to a 89/74 reading which concerned me. I am going to do some tweaking with my probe placements which I am sure would solve the problem.

It sounds like an oil filled space heater is just what the doc ordered in your case. If your room temps are not atleast in the mid 70's you're going to have a hard time maintaining temps.

it's not your thermometer it's your heat source. like JLC said, UTHs are great for hot spots but not for heating an entire glass enclosure. sure you can get a surface temp of 90-something degrees but the UTH will only raise the air temp a few degrees over whatever the room temperature is. you'll either need a heat lamp for the hot side or an oil-filled spacer heater to correct this problem.


goodluck!