Acceptable Daily Tank Temperature change

Tmcgoo13 · May 11, 2017

With summer heat now here, I'm finding that my reef tank temperature varies alot wider especially when running the lights. What is an acceptable range in daily temp variations?

SnookNRedZ · May 11, 2017

The actual temperature shouldn't be near 90. Keep it below that and above 75 ideally. Now that's a 15 degree window here. Now I'll use a 10 degree example here. (i.e. Going from let's say 78 up to 88) in a couple minutes time(5-20), that would be more detrimental than if that same 10 degrees swung over a couple hours (2-4). Hopefully you can devise a solution to make the change more gradual. Again the actual temp isn't the issue (so long as it's between 75-85) hope it helps.

My apex keeps the tank within 1 degree of 78 all day, everyday. And I live in central florida where it gets cookin in the summer. My tank is also in my living room (only 30 total gallons) and I keep my ac set at 74.

Tmcgoo13 · May 11, 2017

Thank you! I keep my house at 74 as well, temps in Nashville get to about the same as FL. In the winter the house was colder, down to 68, so then the heaters did all the work. Now what I've noticed is that the temp swings up fairly slowly over the course of the day. It's 90 gal. When lights turn off, if goes down, but it doesn't however go all the way back down to 78 (heater setting) so then the next day it goes higher, so then I get this gradual up tick over days. Looks like the lights and canopy on the tank are causing the higher heat, which wasn't an issue over the winter.

SnookNRedZ · May 11, 2017

90 gallons of water is pretty good amount when talking changing temp. So that's good. Although the same can be said about cooling it back down.

Canopies and lights will do it every time. Try getting a fan in there to disperse some heat. Keep in mind more air movement across the tank will make evaporation speed up , so keep your eyes on salinity.

Another method would be to get an old (yet clean) plastic bottle and fill it almost all the way with RODI water and freeze it. You could plop one in a sump or float it in a bag to help if it gets to be too high for you. That helped me in my old 20 gallon tank that I had. (Was running canopy w/ t5 bulbs)

Obviously it's only temporary but if your home and can do it, i would.

Tmcgoo13 · May 11, 2017

Good idea, we've had several power outages, have a generator, but the AC won't run with the generator, so putting together the RODI frozen water plan as backup if needed too.

SnookNRedZ · May 11, 2017

Perhaps look into a used window shaker unit you can prop up in the same room as the tank is in just in case of a prolonged power outage. They'll run off a generator no problem. Be nice for you as well in a power outage

Tennsquire · May 11, 2017

Tmcgoo13 said:
With summer heat now here, I'm finding that my reef tank temperature varies alot wider especially when running the lights. What is an acceptable range in daily temp variations?

I run my lights at night to help out with the temps a bit (and I'm not home in the day to enjoy it). I also gave into the Tennessee summers long ago and bought a chiller. I have it set so there's no more than a 2 degree swing (it also controls the heaters).

SnookNRedZ · May 11, 2017

Tennsquire said:
I run my lights at night to help out with the temps a bit (and I'm not home in the day to enjoy it). I also gave into the Tennessee summers long ago and bought a chiller. I have it set so there's no more than a 2 degree swing (it also controls the heaters).

+1 reguarding running the lights later in the evening. That slipped my mind completely. Which is funny cuz my lights come on at 11 and go off around 9 or so. Definitely helps to run the lights at night if your cool with that.

Tennsquire · May 12, 2017

My reef stays between 78 and 80....

H@rry · May 13, 2017

SnookNRedZ said:
Another method would be to get an old (yet clean) plastic bottle and fill it almost all the way with RODI water and freeze it. You could plop one in a sump or float it in a bag to help if it gets to be too high for you.

Why would you need RODI water if the bottle stays capped?

SnookNRedZ · May 13, 2017

H@rry said:
Why would you need RODI water if the bottle stays capped?

Just in case is all. I'd rather have some fresh rodi leak or sweat into my tank than regular bottled tap water.

pickupman66 · May 20, 2017

Amazing how much evaporation can drop a temp. I keep my house at 72. Evap about a gallon a day. My heater runs all year to keep my tank at 72. My tank is open top rimless so that may help.

In tanks past I had to have a chiller. Tank temps can fluctuate but I prefer no more that 5° daily and no higher than 84°.

Lights, canopies and in sump equipment can make a world of difference

vanpire · May 31, 2017

I live in Phoenix and I keep my house at 78 degrees in the summer. The tank temp varies from a low of 79 with lights off and a high of 80.5 with lights on. When the tank gets to 80 degrees, a small fan comes on and helps keep the temperature down.

My tank is a 300 gallon with 3x 250W halides in a floating canopy. Fans do wonders but you do need a good ATO. You should have one regardless.

I also have a 40 gallon cube-ish tank with 6x 24W T5 bulbs. No issue keeping it under 80. No fans required, but is under a AC vent.