temp fluctuation in the day time

[newfly]

I have a 65g tank, with a single 200W heater. Ambien temp in the room is ard 65 ish F during the day and lower at night. No light yet for this tank.

What's weird is the temp in the tank stay about constant at 76.8-77.1 at night but in the middle of the afternoon, the temp can drop to to 76.1

Any possible explanation?

We don't turn on the furnace often. Just to heat up the house fist thing in the morning, and maybe later in the evening. I would expect the temp swing to be higher at night (heat is off, and temp drop to low 60s). The house is well insulated.

I plan to get a second heater regardless.

 

[NanoCrazed]

It's due to lag. My tank drops the mist between 6 - 8A.

Ambient temp continues to peck away at stored heat inside tank until it offsets what you add back in via the heater in there

 

[newfly]

I can totally understand the tank lowest temperature is in the early morning. But in my case , it’s literally mid day like 1-2pm . Early morning and late evening, I’m closer to 77. It magically drop to 76 in mid day.

i don’t think the 1 degree fluctuations will have much impact to the fish. I don’t have coral now. I’m just very curious about this phenomenon.

I need to figure out how to plot the temp on the Hydros control.

 

[Chromis]

76.8-77.1 at night but in the middle of the afternoon, the temp can drop to to 76.1

Maybe your heater is struggling to heat all night, so it never turns off. During the warmer day it finally is able to reach the high temp, turn off and drop back down to 76.1?

 

[newfly]

Maybe your heater is struggling to heat all night, so it never turns off. During the warmer day it finally is able to reach the high temp, turn off and drop back down to 76.1?

it’s entirely possible. The heater adjustment knob are not accurate. I have no idea what the heater is set to. I’m relying on external thermometer probe on the hydros control to check the temp.
Even so, it sounds like my heater thermostat is set to 76degree since ambient temp get high enough for the heater to turn off. Wouldn’t the night temp get to 76 or lower especially if the heater struggling to keep up?

Like I said, I’m planning on getting a second heater anyway as a fail safe . The same brand - Fluval M sold out at Amazon. I should just get the Eheim.

 

[The_Lazy_Reefer]

I have roughly the same setup/ambient temps and can confirm this is weird. My apex keeps the temp within .3 degrees constantly so if the heater you are using is reliable then I would look to the hydros as the possible issue.

 

[The_Lazy_Reefer]

Also does the heater have its own temp control on it?

 

[NanoCrazed]

@The_Lazy_Reefer -- lmao. I thought your profile pic was a troll for a sec there...

 

[newfly]

Also does the heater have its own temp control on it?

Yes. It’s a Fluval M 200

 

[Vhuang168]

Do you turn anything on in the tank at night only?

Reactor, skimmer etc.


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[The_Lazy_Reefer]

Yes. It’s a Fluval M 200

Make sure that’s set above the temp you want it. Even a little higher. Never used that preset heater but most that I have used are inaccurate +- 1-2 degrees so setting that to 80 may help things as if the hydros wants it on but the fluval thinks it’s fine then that can cause the delay.

 

[Vhuang168]

Make sure that’s set above the temp you want it. Even a little higher. Never used that preset heater but most that I have used are inaccurate +- 1-2 degrees so setting that to 80 may help things as if the hydros wants it on but the fluval thinks it’s fine then that can cause the delay.

I don’t think he is using the Hydros to control the heater. Just monitoring the temp.


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[The_Lazy_Reefer]

I don’t think he is using the Hydros to control the heater. Just monitoring the temp.


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Ah then now I’m pretty sure that’s just the fluval heater doing wonky stuff. Figured he had the hydros controlling the on/off of the heater.

 

[The_Lazy_Reefer]

@The_Lazy_Reefer -- lmao. I thought your profile pic was a troll for a sec there...
View attachment 24141

Haha. Those damn trolls taking over again.

 

[newfly]

Do you turn anything on in the tank at night only?

Reactor, skimmer etc.


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Everything is on 24/7. I turn down the Nero to like 5% at night . Even with the lower setting, I still have 30x flow.

 

[newfly]

I don’t think he is using the Hydros to control the heater. Just monitoring the temp.


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Correct. Hydros is just monitoring and will shut off the heater if the temp >83 as a fail safe.

 

[Coral reefer]

If you want a narrower range get something to control the heater like a ranco, ink bird, or apex etc...

 

[newfly]

Let see if the temp is stable with the second heater. If still fluctuate , I’ll go with the external controller as you suggest

 

[Chromis]

@newfly do you have a graph of temp vs 24 hour cycle you can share (I don’t know what kind of controllers you have)

 

[NanoCrazed]

Let see if the temp is stable with the second heater. If still fluctuate , I’ll go with the external controller as you suggest

Just a thought -- it's not a bad idea to put the second heater in your DT. I used to hate it but found that it gives me more redundancy and consistency overall in temp. It still fluctuates but less range.