Kessil

temp fluctuation in the day time

newfly

Supporting Member
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

Supporting Member
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

Supporting Member
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.
 

newfly

Supporting Member
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

BOD
Staff member
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.
 

NanoCrazed

Supporting Member
@The_Lazy_Reefer -- lmao. I thought your profile pic was a troll for a sec there...
1613732458224.png
 

Vhuang168

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

Reactor, skimmer etc.


Sent from my iPhone using Tapatalk Pro
 

The_Lazy_Reefer

BOD
Staff member
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

Supporting Member
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

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


Sent from my iPhone using Tapatalk Pro
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.
 

newfly

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

Reactor, skimmer etc.


Sent from my iPhone using Tapatalk Pro
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

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

NanoCrazed

Supporting Member
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.
 
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