Using an infrared thermometer to measure aquarium temps?

[lobsternoob]

Would an infrared thermometer work well for measuring aquarium temps? Basically I'd want to use it for comparing multiple tanks and buckets at a glance, and I figure it would read surface temp which would be all I'd really need from it. Would it also maybe be possible to target areas of the tank and tell basically by the glass temp on the outside if there are cool spots in your aquarium. I was talking with a friend about doing WC's in multiple tanks, and temp matching the water could be a pain and slow usin traditional thermometers. He said he had an infrared thermometer somewhere, and I'm wondering if one would work well for measuring water temps, kinda curious if anyone has any experience with this, or any reccomendations for a good instant or very fast reading digital thermometer.

[gadget228]

Great question, I have a couple of testers that have that function and will have to do a little testing later today.

[lobsternoob]

A few google searches and some reading I found this paragraph:
NOW CAN I MEASURE THE BODY TEMPERATURE OF A FISH IN MY AQUARIUM?
No, water & glass are transparent for visible light, but for IR, it's almost completely "opaque". One can only measure the temperature of the glass. How about my pet's temperature? By pointing an IR thermometer at your dog, you measure the surface temperature of the fur. What you see is what you get. http://www.clarksol.com/html/tech_bull_infra.cfm

So it looks like you could get an idea of the temperature in areas of your fishtank, but the glass might not be a great measurement because it's in contact with (probably) air that's cooler than the water. I don't know how well this would work out really. I'll be interested to see what you find out gadget, most likely I'll be getting my hands on one of these thermometers in a day or two. I'm kind of thinking you might have to float a piece of paper or something that isnt transparent but will adjust quickly to the surrounding water temp and then take a reading from that or something, but it's possible you could still use it to find out if there were any particular cold spots in a tank I guess.

Edit: Wait, that's totally wrong, I am suffering from lack of sleep and totally misunderstood and overanalyzed that. Because infrared basically sees heat, the water temperature will be read because it sees it in temperature, not in the visible spectrum, so you or I can see through the water to the fish, but infrared can't. If that's the case and I understand it correctly now, an infrared thermometer will do exactly what I want one to. I think I need to get a few hours sleep and then maybe I'll understand it completely

[Brhino]

yes, if you can access the surface of the tank and measure the top of the water, that should give you an accurate reading of the water temperature (at the top of the tank at least). measuring the glass won't work as well because the surface of the glass will be partway between the temperature of the water and the temperature of the air. The glass itself is pretty transparent to IR so you SHOULD be able to get a reading of the water behind it, but it's a bit dicey.

[lobsternoob]

Yep Brhino that's pretty much what I was thinking, measuring the glass won't be that great unless the surrounding air is VERY close to the temp of the tanks. So finding cold spots in a tank might only be viable in a really large tank, or somewhere where there are so many tanks in a small area they dictate the surrounding temperature (wonder if I could find a place like that in my house? ). But it does sound like it will work for what I want, which is a quick read and comparison of surface temps in tanks to hard readings from other thermometers already in the tanks/buckets. Basically I want an IR thermometer to double check on normal thermometers, and act as a faster general guide for bucket temps/etc during WC's. I don't want one for a main thermometer, just as a quick read estimate, so if my friend will give/sell me his for a decent price I'll grab it from him, otherwise harbor freight has an el-cheapo for 20 bucks that I could try. One major problem is that they are very sensitive to moisture, apparently even the screen for the IR reader can mold. That could be a definite problem for using them for any aquarium application. With even just the amount of tanks in my room the moisture level is pretty high. So I'm definitely not going to invest a lot of money in one. Maybe with a little inventive modification or preventative maintenance it can be made to work in a slightly wetter environment.

[gadget228]

Well I can't help you out on this one, both of my testers are shot. One I had was for measuring temps on my RC heli but I forgot to remove the battery's and they leaked and ate it up. The second was a feature in a expensive multimeter that I had to get back from a friend that forgot to return it and it used a laser to pinpoint what your were checking, the laser is real dim and won't light anything up and temp readings won't read anything more than a couple inches away, tried new battery's and it didn't help...

[lobsternoob]

Well, it works pretty well to an extent. I got a brand new one for 19.99 from harbor freight. Their tools don't have the greatest track record for me, but I figured it was worth a try. Basically it tells you a pretty good estimate of surface temps, but if measuring the temp through the glass ambient air temperature does have a major effect on it. It also seems to be affecte by distance, it says it will measure from 6ft or so, but I think the air temp in between must have an effect because the farther away the lower the temp, and if the ambient temp is lower then the temp will go lower with less distance. Tt seems to sync up fairly well with an instant read thermometer though if I use one to measure the very surface of the water I'm checking, oh and water movement from things like filter flow or aeration can have a bit of an effect. It's definitely not something I would depend on for taking the temps in my tanks, but for the purposes I'm intersted in it works pretty dang well. Thanks for trying though Gadget, sorry yours didn't work. Remember I mentioned that the screens can mold/get deposits from sitting in an area thats too moist? that could be what happened with your second one, although that doesn't explain thee dimness of the laser really, since they're probably seperate, I know the laser on the one I got is completely seperate from the actual IR reader.

[gadget228]

Glad to see that you ended up getting some results, I got my cheap one probably 20 years ago and hadn't used it in the last ten years so not surprised that the battery's made a meal out of it, paid over $300 for the good one and going to send it in and get an estimate on repairing it. Moisture could have gotten to it, have had it for about 8 years and it has always been in my toolbox in an unheated barn.