# Marina Brand LCD Thermometer



## speedster239

I was given one of these thermometers for free, but for the life of me I can't figure out how to read it correctly. The instructions read the following: Green indicates the correct temperature (what does that mean???), if green is not visible the temperature will be mid way between tan and blue. What I see on the thermometer presently is a green square with a tan square on top, a blue square below, and a purple square below that one.

Is there something I'm missing here, but why are the blue and tan visible while the green is?

Thanks a million,
Vaughan


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## majerah1

Ah yes,those things are crap,lol.

Marina Floating Thermometer Aquarium Thermometers

Get one like this,found at walmart for a few bucks.I hate the LCDs they are not that accurate and are a waste.And as you can see its hard to tell the exact temp with it.


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## Scuff

The stick-on LCD thermometers only give you a general range of what the temperature currently is, rather than an exact number. This is typically fine for basic tropical fish, however most people (myself included) like to know exactly what their temperature is. This becomes even more of a concern when you factor in that most heaters aren't incredibly accurate (just because you set it to 78 doesn't mean that's what it's at).

The previously posted floating thermometer works well, though I'd recommend the one with a suction cup as it makes placement much easier. The floating ones tend to bump around and inevitably get broken. Or better yet, invest in an electronic thermometer for easy and accurate reading.


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## PolymerTim

speedster239 said:


> I was given one of these thermometers for free, but for the life of me I can't figure out how to read it correctly. The instructions read the following: Green indicates the correct temperature (what does that mean???), if green is not visible the temperature will be mid way between tan and blue. What I see on the thermometer presently is a green square with a tan square on top, a blue square below, and a purple square below that one.
> 
> Is there something I'm missing here, but why are the blue and tan visible while the green is?
> 
> Thanks a million,
> Vaughan


I've got the same LCD thermometer and it's true that they aren't very exact. To be honest, I just go with the most brightly lit number and it assume the temp is give or take a couple degrees from that.

The reason multiple are lit at the same time is because of how they work. They are based on something called thermotropic liquid crystals. Basically, they go through a transition at a certain temperature that changes the way they interact with light. They are designed so that far above or below the transition temperature, they appear black and the black number disappear into them. Close to their transition temperature, they go through some pretty fascinating color changes. The brighter colors allow you to read the black numbers. Each large square on the thermometer is actually a separate indicator with a liquid crystal that has been tuned to a different temperature. eacuse they are so close to each other and the transition for each covers a range of temperatures, there will always be more than one visible. That's why I usually just take the middle or brightest of the ones I can read.

Probably more info than you wanted, but hey, there it is just in case you were curious.


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## snail

I like my LCD because it's easy to read at a glance once you get used to it (Like was said you go by the brightest color), but I think they are better as a back up rather than a primary thermometer. Because it's always in view it clues me in if the heater gets stuck on or something. It might be better to get another one to get your heater set right and use when you need an accurate reading and the LCD will still be useful as a daily rough check to make sure nothing has gone way out of whack.


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## mfgann

Plus the little glass ones can be handy to pull out and measure tapwater temps when you do your partial water changes. I have both, but admittedly I don't really use the sticker much. I'm also not sure how well they hold their accuracy over time.


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## snail

I've had one for years and it seems ok, but I don't really care about it being exact, I just glance at it to make sure the temperature is in the right range, It gets really hot in the summer here and if it gets too high I put the air stone on. If I want to be sure I check the glass one.


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