What's considered a safe temp swing?

jdeb101

Non-member
I'm currently in the initial setup phase of setting up my new Elos Midi36 tank. I just got the sw flowing last night and put a 200w heater in the display to get it up to temp. The 200w is temporary and the tank will be running a 125w once all up and running.

My concern is will the heater be able to keep up with the volume, as I believe I have low flow going through my sump, which is where the Apex temp sensor and my heater will be located. Just looking at the heater on/off cycle as it is now with the 200w I feel perhaps it turns on too frequently and takes a while to raise temp back to 79. Thoughts?

temp swing.png
 
The temp variation shown is negligible. The 125 watt heater will take longer to heat the water, but as long as it can maintain, there is no problem.
 
Coral can be fine with 5F swing day and night. There is a scientific paper show coral would have better immune system with the swing


Sent from my iPhone using Tapatalk
 
In the ocean, there is cold water rising from the deep. The ocean swing more than expected.


Sent from my iPhone using Tapatalk
 
I guess what I'm more concerned with is how frequent the temp dips throughout the day. Looks like the temp drops a degree within 1-2 hours and then takes about 2 hours or so to go back to 79. Is that frequent of temp swing, even though just a degree ok? Additionally, I'm concerned with my electric usage with the heater basically being on almost half the day. lol
 
There's no difference in a 200w heater being on half the day or a 400w heater being on a quarter of a day. Assuming the efficiently in heaters are equal(it should). You're problem is not the heater, but it's the hysteresis of your controller. Tighten up the window and it'll be more stable. For example, if the nominal temp is 78 and you set the controller to turn on the heater at 77, there's a 1 degree drop until the heater is being called on. If you set it to 77.5, it would be more stable.
I set the smallest hysteresis the controller allows. For a profilux, it's 0.2degrees. My nominal temp is 76 with 0.2 degrees hysteresis. Temp swings from 75.8 to 76.0 at night. With the MH on, it stays above 76.
 
There's no difference in a 200w heater being on half the day or a 400w heater being on a quarter of a day. Assuming the efficiently in heaters are equal(it should). You're problem is not the heater, but it's the hysteresis of your controller. Tighten up the window and it'll be more stable. For example, if the nominal temp is 78 and you set the controller to turn on the heater at 77, there's a 1 degree drop until the heater is being called on. If you set it to 77.5, it would be more stable.
I set the smallest hysteresis the controller allows. For a profilux, it's 0.2degrees. My nominal temp is 76 with 0.2 degrees hysteresis. Temp swings from 75.8 to 76.0 at night. With the MH on, it stays above 76.

Thanks Nick. Makes sense. I have temp set to 79 and to turn on heater at 78, so I'll adjust to maybe 78.5 and see how it looks.
 
Adjust to the smallest hysteresis as your controller allows. You want that heater or fan to kick on as soon as the desired temp has risen or fallen.
 
Adjust to the smallest hysteresis as your controller allows. You want that heater or fan to kick on as soon as the desired temp has risen or fallen.

I'm controlling it with an Apex, so I could set it down to .1 degree difference. I would think the frequent on/off cycle of this close a temp would not be a good thing for the heater?
 
I don't know. I've been using 0.2 and I have not had any issue with the Ehiem heaters I'm running. The thing is, if you really care for it. You don't want a quick and drastic change in temperature. Corals stress due to many other variables and in combinations of those variables. Some tank can handle +/4 degrees because everything else is perfect. Some tank see stress of corals with +/-1 degrees because ALK is off or some other nutrients level is too low, etc.
Are you worrying about your corals or your heater's life?
 
I don't know. I've been using 0.2 and I have not had any issue with the Ehiem heaters I'm running. The thing is, if you really care for it. You don't want a quick and drastic change in temperature. Corals stress due to many other variables and in combinations of those variables. Some tank can handle +/4 degrees because everything else is perfect. Some tank see stress of corals with +/-1 degrees because ALK is off or some other nutrients level is too low, etc.
Are you worrying about your corals or your heater's life?

Both. I'm also using Eheim (Jager) heaters.
 
So based on your chart, it looks like the tank is doing 1.25degrees cycle in about 2 hours. Maybe tighten the window a bit?
Here’s mine. Sorry, I’m looking at this with my phone. Over the span of 2 months. The spikes are from the MH being on. The oscillation in between the spikes are when the MH are off and you can see the windows is about 0.25 degrees.
4C067793-DEBA-4F34-827E-AB1957A37A7B.png
 
As This is Me have said. I have my heater with a hysteresis of 0.5 degrees. The heater has now 4-5 years old and still doing fine.
 
Here is my Apex graph. The big swings in Temp were last week storm outages.
775838a895174c603c20c3590ecddefd.jpg


Sent from my SM-G955U using Tapatalk
 
Alright guys... so I just got back from a 4 day vacation in FL and noticed some concerns while away. Before I left, I lowered my house thermostat to 55 degrees. It didn't take long for my Apex to send me an alert that my tank temp fell below 77 degrees, and it dropped down to as low as 74 degrees the few days I was away! So I guess my 150watt Jager heater cannot keep up with the tanks demand? Strange, as it is rated for 53-79 gallons on BRS site and My tank is 36g and sump I would guess has 5 gallons maybe? Well below the heaters rating.

Also I shortened the window of my heater to go on at 78.7 and off at 79, but I noticed my heater is almost constantly on throughout the day. Seems like it's off maybe 10-20 minutes between cycling back on.

I'm curious if these issues have something to do with the return pumps flow rate being too slow? I have it set on a somewhat low flow rate. I put a temp probe in display to see if any discrepancy between that and sump and it's only about .3 degrees cooler.

Might also be worth noting that the heater and temp probe are in sump.
 
Upcoming Events

April 21, 2024
Paul B
Club Meeting

Back
Top