Powerheads create a LOT of heat.
 

At the last Mars meeting, I picked up 4 nice corals. Came home, set up my quarantine tank, and began acclimating. Since it was after midnight, maybe I wasn't thinking as clearly as I should have. I decided instead of just setting up the usual air-pump, I would treat the corals with more water movement - and put in a powerhead.

Saturday mid-morning, after a trip to Home Depot, I noticed one of the corals in the Q tank was bleached. To make a long story short, the temp in the Q tank was 100 degrees! Since I do not run a heater in my Q tank, there was only one source of heat - the powerhead. I did a water change & brought the temp down to normal (78), but I still lost all 4 corals. :(

The moral of the story: even though the weather is cooling off, high temp can still be a problem, especially with a large powerhead in a small tank. If we can learn from each others' mistakes, maybe we won't lose as many precious animals.

i had a similar problem.. was mixing a new batch of water for a waterchange.. had a mj1200 in about 3 gallons of water...let it sit over night... next morning.. it was nearing 90 degrees

Ph's dont put off that much heat. I run 3 in my 50 and my water stays at 81 constant. They put off some heat, but not enough to make the water 100+

Your PH was faulty.... Only thing to it.

Aslo, Doing a water change and taking a living thing from 100+ to 78. Bad, will do major harm.

Thats a pretty bold statement.
If it was a QT tank, more than likely it wasnt a 50+gallon tank which would explain your different experience. On a smaller scale, ya, they put off enough heat without close attention can easily overheat a small tank. I had the same experience that sumyungviet had when I was mixing water, and almost burnt my hand.It was that hot. With one pump in my 'ol 15g the temp stayed a consistant 80 degrees, id say ya they definately put off some heat; and can be lethal if not monitored. Sorry for a hard lesson learned :(

-Justin

It depends on the "heat sink"....and how much energy can the volume of water absorb before raising the internal energy(temperature) of the water.

but it really depends on the brand, and the individual thermal effeciency of the powerhead.......to quantitativly determine how much it would increase the waters temp.

In a smaller tank with a couple of pumps......yeah that needs to be considered and watched.....but as the water volume and the low temperature sink increases.......it wouldn't affect it as much and become a non issue.

Look at the heat issue in nano cubes just from the overhead pcs for instance as an example of how little of a heat resevoir there is in 12g....add a pump and boom.....your over capacity absortion wise......overheat city.

I don't use a heater to make up water for a water change.
I let my mag 5 run for 3 days (it only take 6 hours to heat the water)

In 6 hours a mag 5 in a 5G bucket makes the water 97-99 degress.

Then I let it cool for 4 hours to get my 80 for my WC.
Yes depending on the powerhead they really put off the hest.
~Steve~

ph's are definately a heat source to reckon with. most nano owners swap the stock pump for a maxijet. in particular, i took out my 32w stock aquapod pump and replaced it with 2 maxijet 900s which totaled 17w. huge difference and my water temps were consistently 2 degrees cooler this summer after replacing the stock pump.

MJ1200 is 20 watts and not all of that goes to heat. Normal heaters are 50+ watts. Why you'd use a big pump in a small container for several days is beyond me. Make up water needs only 24 hours of moderate mixing. In a small container you can try one of the smaller MJ or minijet pumps (5-7 watts).

This is one reason why I hate submersible pumps and powerheads. I try to keep them to a minimal. My 120G has two Tunze 6000's (total of 30 watts) on a controller. 30 watts for 3700GPH is great! As much as some people hate Seio Pumps, they give a lot of water movement for the amount of energy they use.

When I mix water (usually 30 gallons at a time), I start of with both my Mag 9.5 and Mag 5 going. This allows a lot of water movement to help dissolve the salt (usually 12-24 hours). Unfortunately, I don't always get to changing the water immediately (sometimes it takes me a day or two - or even a week) - so I just leave the Mag 5 to keep the water circulating.

Minh