New to the Hobby (long time fish keeper)

[Karling]

Hello - I have a question and YES I searched for a bit before making an account

My father had a HUGE octagon tank when I was young and I spent a lot of time helping him, so I have some history of saltwater.

I've had 100g 60g and 50g Cichlid tanks among many other freshwater tanks with some sport fish in them when I was young and dumb, I raised a pair of minnows that wound up being 2 large mouth bass.

Anyways!

I just put up a 125g Saltwater tank with sump system. Mixed up the salt water and set it at 1.025. its been cycling for a couple days and without the heater in it right now it fluctuates between 80.7 and 81.5 through the day. The lights are NOT on currently and i have opened up the base of the sump and running a box fan through there to see if that cools it down. My 4 year old has a freshwater system on the 2nd floor it is 20g and holds at 77 degrees with the heater coming on a few times a day. The house is set at the below temps and we rarely get away from those temps.

72 Summer 68 Winter Daytime
68 Summer 64 Winter Night Time

Any Idea why the heck my tank is holding so much heat when the ambient temp in my house is 72?

 

[MaxxuM]

It can take a few days for that many gallons to cool down if the main water source was over 80. You could put bags of ice in zip-lock bags bringing the temperature down to 77 and see if it creeps back up . Did you use at least 2 thermometers to confirm? Same with the room that it's in. Another issue could be an overheating main pump.

 

[ichthyogeek]

Welcome to the forum!

As for why it's holding so much heat, it's a function of multiple factors, which include the amount of stuff in the tank in addition to the water inside the tank. Water has a high specific heat, so it can release a relatively large amount of energy before it changes temperature, and vice versa (it can take a lot of heat energy before heating up significantly). Rocks/Sand in the tank can also do the same, but to a lesser degree. In addition to this, any electrical equipment in the tank (pumps, etc.) can also heat up the tank as they run. Glass is also a good insulator as well. Like MaxxuM said, if the water you put in the tank was over 80F, it's going to take a while for all of that water to lose its energy (i.e. heat).

As you know, evaporative cooling via airflow can help with lowering the tank temperature. Conversely, if there's minimal airflow (i.e. covers), tank temperature can take a long time to go down.

 

[Karling]

Thanks guys!

Here's more facts.

2 thermometers in the room and in the tank confirm the temps. 100% agree with that.
The crappy heater element I got with the tank had the knob at 88... I noticed it a few hours after putting in the saltwater and getting the sand and rocks placed. I turned it down to 78. The water that night was at 85 and has been dropping since. I just figured it would be a lot quicker than 36 hours for it to get to 78 degrees as well as it seems to have stalled. But again, saltwater holds heat along with other issues. I am wondering if i should drill holes in my hutch to allow airflow, although I was wanting to keep that closed in for winter time ambient air temps.

I just ordered 3 new pumps just to be sure its not the pump causing the issue... but the water coming from the pump is the same going in as it is going out... at least by setting my thermometers at both the entry and exit point...

I wont be putting anything live in it for a couple weeks so no need to worry about cooling it with frozen bottles or anything. Just more of a why the heck is this happening post...

 

[MaxxuM]

As the water gets closer to ambient temperature cooling will slow.

Stability is key so I'd be thinking about your winter months more than your summers. Two heaters with auto-shut off sensors would put some redundancy in your system. A backup battery that could provide flow during power outages would be good too. I use one meant for computers for my DC pump and it can run it for quite a while. If you're planning on having your tank full of expensive corals you might also look into a generator. I bought one for my house and it saved my tank when I lost power for over a week when a hurricane relocated my electrical pole into the next county!

 

[neiltus]

well, your heater works well!

I would cut the heater off and just give it a few days to settle. I run my mixed at 75-79

 

[Karling]

Thanks all. ive shut the heater down. It is dropping down but slowly... I ordered new pumps just to be sure.. However if it can self maintain this well, i think i'm headed in a great direction!

 

[Karling]

UPDATE: we are maintaining at 79.0 for the past 12 hours, i have backed off the heater to 78.0 to see if that temp will drop over the next 12 hours down to 78.0. My only concern is what happens when i put the top back on, will it rise or maintain? we shall see.