Fluctuating Temperature at Night..

[Bree7]

Hello, Simply Members!

I have a quick question.. is it normal for tank temperatures to lower during the night?
My heater is set at 86* but it runs a little low, so that takes it to 84-85* which is what I aim for. During the day time, the temperature is correct, at 84* or 85*.

However, when I wake up in the morning and check the tank, the temperature has dropped to 80*-82*. Is that normal? Is the fluctuating temperature going to hurt them? I've heard it can be bad, but I don't know how to keep it constant...?

I have another heater, but I use it to prep the aged water. It seems like the heater should keep a constant temp, and it does during the daytime, but at night it lowers slightly (by a couple degrees). Maybe because the window is cracked open at night? Or there is (obviously) less light in the room to generate heat? After a couple hours into the day, it's back up to 84/85* for the rest of the day.

[David Rose]

The change is gradual and only a couple of degrees, so I don't think you have anything to worry about. I have two tanks in my four season room where the room is not heated at night in the winter time or cooled in the summer time and they fluctuate a couple of degrees as well with no ill effects.

As for the heater itself, it depends on the brand and tank size it's rated for. Not all published ratings are true and only experience will tell you differently. Eheim Jagers are the best IME and I always have two heaters in my tanks to maintain an even consistent temperature with in a 1-2 degree fluctuation at most.

I've also had good experience with my Finnex w/controller's from Kensfish.com (not the digital kind that reset to 81F after a power outage) that are the dial a degree type. They even have a model that has nice safety features with auto shut off if exposed to air or exceeds the desired temp so as to not cook your fish if the thermostat sensor fails.

[flyman767]

I agree with david...years ago, I had one large heater vs two small. Although the wattage was equal the two small will keep the temp much more steady than one big one will. Personally, now I keep three small..and my temp locks at 84.8 degrees...Ray

[johnny313]

A Ranco controller would stabilize the temp 24x7

[kaceyo]

IMO, it's best not to have that much variation in temp. The more stable the environment is, the more succesful it will be. With a properly working heater (or two), the right size for the tank, there should be very little to no variation.

[David Rose]

Don't take this the wrong way, but doesn't temperature drop at night in nature for all of us and yet we thrive. Just seems natural to me.

[kaceyo]

Don't take this the wrong way, but doesn't temperature drop at night in nature for all of us and yet we thrive. Just seems natural to me.

That's true Dave. However, living in our tanks is a far cry from nature and a poor substitute. Many things that our fish could tolerate in nature without flinching will cause problems over time in our tanks.
Stability is the key whether it's in pH, temp, TDS, light duration, feeding times etc etc. The more things that are as stable as possible, the less stress on the fish. Less stress equals healthier fish.

[joshuajames]

could be from having your light off at night.my light makes a lot of heat and i put risers under it.also if you have alot of bubbles at the surface it could heat the tank.like a pool cover type thing.just another suggestion tho.i thought i was having heater problems and all along it was my light. good luck

[David Rose]

That's true Dave. However, living in our tanks is a far cry from nature and a poor substitute. Many things that our fish could tolerate in nature without flinching will cause problems over time in our tanks.
Stability is the key whether it's in pH, temp, TDS, light duration, feeding times etc etc. The more things that are as stable as possible, the less stress on the fish. Less stress equals healthier fish.

Makes perfect sense...thanks Kaceyo my friend!

[Jhhnn]

Try leaving the lights off for a day, check the temp that way. Your heater may really be set for 82-84... Check the heater in the morning, too- if it's cycling on/off, then that's the actual setpoint temp.

Keep the tank lids tight, so heat won't escape as easily. Insulate the back and bottom (if the tank is on an open metal stand) using 1/2" rigid foamboard or reflectix. MMorris covers her tanks with reflectix at night, iirc. It can't hurt.

If none of that works, consider that your heater may not be strong enough, regardless of the wattage rating. You want an honest 3-5W/gal, tending towards the high end of that. I'm with David wrt Jagers- once calibrated, they're great. They are longer than other brands of the same rating, just so you know...

[XeBurnout]

I understand your point Kacey and you could be right to an extent. But my feelings are that not exposing the fish to any changing conditions might seem nice but it may do harm if conditions ever got out of your control. If for example you lost power overnight, a fish that is exposed to normal temperature fluctuations may not even notice, but one who has lived their entire life within four degrees of your setpoint may become stressed.

Being able to cope is a natural and good thing. It's what happens to us when we exercise or even get sick once in awhile. If you lived in a bubble the first time you were exposed to a flu virus you might keel over, and someone who never did anything in their life but push papers around might starve if they lost their job and had to pick up a shovel!

I agree a tank is a poor substitute for nature but in many respects it's because the fish is too pampered. The water chemistry stinks and not very much room, but other than that these little guys have the life. All their needs taken care of, never having to really work for a meal, girlfriend dropped in front of you, no piranhaa after you. I'll bet they live way longer in a good aquarium then they ever would in the wild.

I know I'm rambling a little but I think things, even fish, benefit from a little toughing up once in awhile.

Having said that I think I might freak out a little if the temp dropped twenty degrees over night. There is of course reasonable limits.

Phil

[kaceyo]

I understand what your saying, but I dissagree. I think that the healthier the fish is, the better able to withstand stress it will be. I don't believe that allowing them to experience stress will condition them to be able to better withstand stress in the future. If it did, fish that were kept in less than desirable conditions would toughen up and have fewer problems over time, but I don't see that happening. The people who take the best care of their stock, paying attention to the smaller details of keeping them stress free, will usually have the healthiest fish.

I understand your point Kacey and you could be right to an extent. But my feelings are that not exposing the fish to any changing conditions might seem nice but it may do harm if conditions ever got out of your control. If for example you lost power overnight, a fish that is exposed to normal temperature fluctuations may not even notice, but one who has lived their entire life within four degrees of your setpoint may become stressed.

Being able to cope is a natural and good thing. It's what happens to us when we exercise or even get sick once in awhile. If you lived in a bubble the first time you were exposed to a flu virus you might keel over, and someone who never did anything in their life but push papers around might starve if they lost their job and had to pick up a shovel!

I agree a tank is a poor substitute for nature but in many respects it's because the fish is too pampered. The water chemistry stinks and not very much room, but other than that these little guys have the life. All their needs taken care of, never having to really work for a meal, girlfriend dropped in front of you, no piranhaa after you. I'll bet they live way longer in a good aquarium then they ever would in the wild.

I know I'm rambling a little but I think things, even fish, benefit from a little toughing up once in awhile.

Having said that I think I might freak out a little if the temp dropped twenty degrees over night. There is of course reasonable limits.

Phil

[Dkarc@Aol.com]

A small drop in temp like that wouldnt make any noticable difference in their overall health or apperance. I wouldnt say the temp fluctuation is extreme, but it is definetly noticable. Keep in mind the temp would drift to the lower number, not a sudden drop. Since we're not talking about extreme swings (86 down to 76 for example), I dont think it will hurt anything. IMO, nothing to worry about.

-Ryan

[Dan]

A small drop in temp like that wouldnt make any noticable difference in their overall health or apperance. I wouldnt say the temp fluctuation is extreme, but it is definetly noticable. Keep in mind the temp would drift to the lower number, not a sudden drop. Since we're not talking about extreme swings (86 down to 76 for example), I dont think it will hurt anything. IMO, nothing to worry about.

-Ryan

100% agree.

[nc0gnet0]

Originally Posted by Dkarc@Aol.com
A small drop in temp like that wouldnt make any noticable difference in their overall health or apperance. I wouldnt say the temp fluctuation is extreme, but it is definetly noticable. Keep in mind the temp would drift to the lower number, not a sudden drop. Since we're not talking about extreme swings (86 down to 76 for example), I dont think it will hurt anything. IMO, nothing to worry about.

-Ryan

I agree with this as well, and as long as we are talking in the +/- 2 degree range nothing to worry about in my opinion, it might even be healthier as others have suggested. However, there will be exceptions such as treating weakened fish.

It may be a sign that your tank is on the verge of being under heated in the watts per gallon range. I am not buying into the lights being the main culprit here, not with a proplerly functioning heater. The only time this should happen is when the light put off enough heat to totally overcome the setpoint of the heater. While I agree that they will add heat, this should only result in the heater cycling on less during the day and more at night.

The problems with ALL in tank heaters with internal thermostats is, well, that they have internal thermostats. Terrible design flaw. Not to mention they are all using 30 year old technology. Ideally you want your heater at one side of the tank and its thermostat at the other. You can help alieviate this problem by mounting your heater horizontally about 1/3 up from the bottom with an airstone directly underneath it to keep the water circulating around the heater