Heater is going berserk - what to do?

[chicagojo]

I have a single betta living in a 2.5G heated tank, heated with a Hydor Theo heater. The water temp is typically 80F but yesterday I noticed it had crept up to 82 or 83 prior to the scheduled 100% water change. I did the water change with 82F water, not wanting to cause any sort of temperature shock, but turned the heater down when I put it back in the tank. Earlier today the temp was up to 84F so I turned the heater down another click and now the water temp is at 85, the heater setting is all the way down at 76 and the heater is still ON (it is supposed to auto shutoff when desired temp is reached).

What should I do? It's really cold here so going without the heater isn't an option. I don't have ready access to a new heater - I had to mail order this one and it took weeks to come. I do have another old Hydor Theo but it was in a tank with a fish who died mysteriously so I'm hesitant to re-use it. How can I best get the water temp back under control without stressing my poor fish (who seems quite happy at the moment, I'm just worried it's going to keep getting hotter and then he won't be so happy)

ETA: it's not due to water evaporation - since doing the 100% water change yesterday the water level hasn't changed noticeably.

[callistra]

Sounds like it's broken. You need a new one. I've had no luck with this brand myself, but others like it.

[Phaydra]

Originally Posted by chicagojo

I have a single betta living in a 2.5G heated tank, heated with a Hydor Theo heater. The water temp is typically 80F but yesterday I noticed it had crept up to 82 or 83 prior to the scheduled 100% water change. I did the water change with 82F water, not wanting to cause any sort of temperature shock, but turned the heater down when I put it back in the tank. Earlier today the temp was up to 84F so I turned the heater down another click and now the water temp is at 85, the heater setting is all the way down at 76 and the heater is still ON (it is supposed to auto shutoff when desired temp is reached).

What should I do? It's really cold here so going without the heater isn't an option. I don't have ready access to a new heater - I had to mail order this one and it took weeks to come. I do have another old Hydor Theo but it was in a tank with a fish who died mysteriously so I'm hesitant to re-use it. How can I best get the water temp back under control without stressing my poor fish (who seems quite happy at the moment, I'm just worried it's going to keep getting hotter and then he won't be so happy)

ETA: it's not due to water evaporation - since doing the 100% water change yesterday the water level hasn't changed noticeably.

Put the old heater in a glass of water, in the tank temporarily, while you wait on a new one in the mail. The tank should stay heated that way without exposing your fish to any mystery disease. You have to be careful not to mix the tank and glass water of course but it should be okay short term. It could be anything that holds water just so long as it's as tall or taller then your tank.

Edit: I would also order a backup heater as well and test it before I store it.

[Perseusmom]

Sorry you having troubles with your heater. I dont think I would trust to leave it in at this point. If it would stay at 84 that would be okay but now if its no shutting off it could very easy overheat the water. You could put a towel over the tank to keep the heat in over night if you can at all possible get a new heater tomorrow. You could express overnight one from Amazon but I guess that would cost alot. I just dont know what else to tell you maybe others will have some ideas.

[chicagojo]

Thanks, everyone. I had to leave the house just after posting the OP so, in a bit of a panic, I disconnected the malfunctioning heater and stuck the backup from my old tank in there. Over the next several hours, the water temp went down to 80, where it is now holding steady. I wish I had seen the post with the idea about quarantining the heater in a separate container just in case, but I didn't see it until after I got back just now. I'm going to order a new heater right away and hope for the best. The fish seems to be holding up very well given all the excitement. I'm just glad I noticed what was going on or he'd have been boiling before long!

[Phaydra]

All that matters is your boy is in the correct temperature water. I've had a heater malfunction and boil 5 neon tetras before. Was not a happy camper that morning when I got up.

[chicagojo]

Originally Posted by Phaydra

All that matters is your boy is in the correct temperature water. I've had a heater malfunction and boil 5 neon tetras before. Was not a happy camper that morning when I got up.

Ugh, I can only imagine. I'm so glad I caught this before we had something like that happen here! Of course now I'm going to wake up in the middle of the night and feel the need to check the water temp just to be sure... :)

ETA: Meanwhile, new heater is ordered and on the way!