Backyard Aquaponics
A place to discuss aquaponics

By reliable, I mean: Strong and break resistant. Good waterproof design if digital. Accurate.

Here's my experience: I've had two unreliable types in the last year. The first one was the glass type with mercury, and what looks like lead balls in the bottom. It was meant to stick on the side of the tank with a suction cup. It probably worked better on glass, but didn't have much holding power on poly plastic, and would float around.

Who knows what happened, but it shattered in the tank....

Next, I picked up a cheapo digital one, and it lasted a few weeks, maybe a month. I thought it might be the battery, so I opened it to find it all rusted. It was rusted pretty fast, and though the probe was in the water, the brains were kept from getting wet, about 8 inches or more from the water. But it still got moisture damage.

SOOOO, what have you had a good experience with as far as thermometers go?

Hi mate, my thermometer are my fingers and the fish.
PH is all I check nowadays and having hardy fish helps.
Here, trout and Barramundi are fish that require close attention to temps and when I had trout, having a large volume of water, or thermal mass, reduced temp swings and I did monitor closely as summer approached. I used a pool thermometer but didn’t leave it in the water and still only checked after a hot day or when the fish went off their food.
The last thing I’d want is the thermometer contents in the water however minute the quantity.
If using an electronic measuring device try for a stainless probe so as not to contaminate the water.

Some TDS & PH pens have it,when you feed the fish take sample of the water & measure it.
I think I have the one you described first,the one that floats & has little balls in it.I've got it straped to a pipe because it floats and never sticks with its suction cup.It has a green background with a red line that tells the temp.The glass is thick on it though.

For a year or so I used an Elitech USB thermometer that records the temp at intervals, then you upload the data and view the graph showing your daily temp swings, min / max, etc. I really liked it but it was not a robust outdoor device and eventually succumbed to moisture. I would not recommend it.

Now I use a wifi thermometer that does the same thing but uploads data directly to my phone. For about the same price I opted for a temp controller model since it does more for the same cost, and I was already using something similar to heat my tilapia tank in the winter. So now I use an Inkbird ITC 308 wifi model. I recommend these though they do cost a few bucks. I have had the non wifi models in operation for several years and they work well, though be mindful of the max wattage rating. I keep them out of the sun and elements. They have a nice long temp probe and cord. I use toddler protective plastic plugs in the outlets I am not using to further prevent moisture damage.

Ha! True Skeg, a finger is relatively unbreakable....I've almost broken mine a few times, but they never actually broke.......
I can see your logic, and i love the simplicity of how it functions. Also, it's always with you... I tested out my finger today, and the temp reliability is off by a few degrees. I'm working with hardy fish, but have been considering giving tilapia a go.

7341, I had a ph pen, which also read temp, but it was very short lived...It was a 14 dollar pen from eBay....had good reviews, but simply quit working for me after a few months. I know that you probably get what you pay for with those kinds of things, good suggestion though.

DSt.John, A temp controller actually looks like it would be a solid investment, but I do have limited plug real estate...I like the readability and it seems like it would be pretty accurate. What temp do you maintain your tilapia at?

I have a cold tolerant strain that survives down to 65 degrees, but they really don't thrive until they are above 70. So my heater is set to come on at 66.