Reliable Thermometer Brand??

[jolliolli]

Just wondering if anyone knows a reliable brand of fully submersible aquarium thermometer. I set up my discus tank today (180L with aqua one 200W heater) and seemed to be getting strange readings on my hailea brand digital thermometer, so i added two other thermometers at the same height and same position in the tank, this is what i got:

Heater thermostat set to 26.5

Hailea digital thermometer 30.2 degrees

Aqua One digital thermometer 25.2

analogue (mercury thermometer 32.5

So they are all very different, I'm inclined to believe the aqua one thermometer as its brand new today. The hailea is around 3 months old, i've replaced the battery but it still seems stuck around the 30 degree mark. The mercury thermometer never seems to drop past around 26 degrees.

So... which brands are reliable, i suspect the hailea and the mercury thermometer are stuffed as the hailea used to display temp readings of 28 degrees in my 300L tank despite the fact the heater is wound down to the minimum.

My other question is the heater in the tank is 200W aqua one, I have a spare transonic 300W heater should i use this instead (don't know what transonics are like as a brand

[Aquarium Dude]

Not looking at readings I would probably Go with the mercury one, electronic things have a habit of going wrong. A chemical change should be more accurate I would have thought

[jolliolli]

I've ruled out he mercury one as being correct, i found a small hole in the thermometer and it had filled with water, so that ones stuffed. Im now pretty confident the aqua one is correct and the hailea is stuffed. I put them both in my unheated goldfish tank, aqua one gave a reading of around 17.7 whereas the hailea said 24.5 (which seems way too high for an unheated tank). Also seems to fit with match the heater thermostats.

[smidey]

my aqua one digital is around 1.5 degrees hotter than my mercury item

[jolliolli]

well i went heater mad and bought several to solve problem, a mercury one, another aqua one digital and an aqua one one where only the probe is inserted. The result of all this is that the hailea was indeed stuffed (dont' know why only a month old) and hte original mercury one was stuffed. So now i know and i have 2 main tanks with 5 thermometers

[Alan]

When buying a thermometer from anywhere, you get what you pay for.

If you get say 5 or 10 of them and compare the readings on all of them.

You will probably find 6o difference, a few high, a few low, and a line of them about equal with one another.

Buy those ones.

Now neverIMO, trust the temp reading on your heaterstat.

To test it.

Heat a small bowl of water so as the thermostat is controling the on/off, read the thermostat setting, then take a thermometer reading.

Bet it's different.

So now make a note, maybe write it on the plug H/S26 = Th24.

That way you will know that that H/S is 2o out, or whatever the diff is, and you can make the appropriate adjustments.

Now heat your tank after making the necessary adjustments to the H/S to match the Th. and when it is cutting on/off check the temp again.

It should now be reading what you expect it to be reading.

If it's not, throw it all out and keep goldfish.

[new zealand discus man]

Most reliable is the Dairy Company ones used in milk vats..Floating in plastic drop protection sleeve.Dont always save.

Wrightsons ,Profarm or simular at about 20 bucks..Other than that smith biolab for lab grade..Cheers Phill