I have a AllGlass 300w heater on my 72 gallon bow. A couple days ago I was getting a temp of 75 which I was happy with. I decided to turn up the temp to around 80 to help along the fishless cycle. Yesterday my top fin tank thermometer read 80. So I double checked the water temp with my calibrated Vernier usb temp sensor and it read 81.9.

I turned down the thermostat back to where I had it when it was 75 degrees and the tank temp hasn't moved. Last night I turned the temp down all the way and it's still 81-82 this morning. Is my heater shot?

I planned on upgrading to a 300w Hydor in the future, but if I need to now I better. Just wondering if you thought the heater was going bad?

sounds like it, but it might just be that the water isn't cooling off enough. what is the room temp? I personally would get 2 heaters instead of one, in my 75 I have 2 200 watt heaters(one on each end) and it keeps my tank a good even temp all around. plus online, it cost me less than buying one big 300-400 watt heater

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Frontosa Fanatic

Is the heater off?

I had it set to 72 on the heater and it was 75 in the tank last week. I wanted to bump up the temp for the fishless cycle so I turned the heater to 76 and the tank has been 81-82 since then, I was looking to get 79-80. Two nights ago I dropped the temp on the heater back to 72 and the temp stayed at 81-82. Lastnight I dropped the temp on the heater all the way and it was still 81-82 today.

I am probably just going to order the hydor 300 and go with that. I have a 100w and a 250w that came with the tank too but I'd rather have an inline heater and declutter a bit.

Screw it, just bought the Hydor 300 inline.

What I was saying is that if you turned down the heat and the heater turned off, then your tank is just taking a little while to cool back down. Unless you have one of the heaters that don't have some type of "on" indicator on it, then I would recommend one. Heaters are sometimes difficult to get them adjusted where you need them. None of them are good enough to exactly give you what they are set at, unless they are digital.. I personally don't think anything was wrong with your heater. But if it makes you feel better to get a new one....... You could however, experience the same type of thing with your new one. Forget what is on the dial. Use your therm to set it.

it has an orange light that is always on no matter where I turn the dial. I just feel better having a new heater before I get some fishies in there.

Good plan. I lost my breeding pair of angelfish to an over-active heater. It was doing what yours is doing - refused to cool down even though I had it turned down all the way... One day it just decided to crap on itself and cooked my poor fish. :( I felt so bad for them. Plus I could no longer trade their babies for fish food and other supplies from the LFS.