Depending on the temperature controller and the water movement around the heater, The water temp should be fairly consistent whether the heater is on or off.
If you’re getting big enough temperature swings in the tank that the fish are huddling around the heater, you either have extremely poor water circulation or the heater is way undersized for the temperature differential between the set point and the room temperature
Thanks. FYI, to clarify, this is not a heater situation I have, just a question to help me understand the many things I'll have to do to monitor temperature, test new heats, new systems, etc. So thank you for the info! Very fun stuff. My first actual tank will probably arrive tomorrow, so I am in the stage writing up the equipment configuration (on paper) and adding (on paper) things to it piece by piece.
Just on the topic of heat -- keeping tank size in mind when designing a system; choosing equipment that covers your expected technical & size needs; creating a maintenance plan that includes temperature checks and journaling; monitoring and adjusting temperature; know the "wiggle room" in temp ranges (the ultimate optimum temp range, the acceptable temp range; the concern/emergency/take action now range); and then, the Concern & Emergency Action plans you have to have written up in case action is indicated -- there is SO much to learn, and it is so fun.
It is all very new. Right now, in addition to the small tank arriving tomorrow (I hope), I have ordered:
- a heater & filter bundle (boxtech, it's good deal bundle, so if the heater is too much, or the filter is not exactly the right type, one or both can be returned or kept for a 2nd tank)
- an indoor temperature and humidity monitor and recorder, to help me start paying attention to the ambient influence on the tank, and another safeguard;
- an API freshwater master test kit;
- an air stone / tank bubbler [SIDE QUESTION TO SELF -- I noticed my filter (above) is an oxygen pump, so I need to check whether the air bubbler redundant or both are need]
- water conditioner
- tank scrubber brush
ALSO on the side, I have a small terrarium coming so I can keep non-aquatic plants too. My freshwater tank visual design is modern architecture / cubist glass house theme, so the terrarium will be an adjunct/adjacent "building"
- small clear 3" x 3" x 2" square bowls for either the terrarium, or for in-tank isolated planting. Three in a row, or in a corner, might look nice for aquatic plants, and allow me to also keep part of the tank floor just glass, no gravel or substrate. Still researching and asking around.
