Another Heater Question

[heavyp83]

In a tank with only sponge filters, do you find that your heaters turn on and off frequently. Like since there isn't much circulation in the tank, the heaters don't come in contact with all the water. I was just wondering, thanks! :P

[Smokey]

yes you are right. A tank will develop "cold water spots". Some people use a small powerhead to circulate the water, others just put in an extra airstone at the opposite end of the tank.

[korbi_doc]

:bounce2: :bounce2: Smokey's right! Only couple of my 20g tanks have just sponge filters & I have sev'l airstones to aid the circulation. Dottie ;D ;D

[RAWesolowski]

A secondary reason for "short" cycles with heaters may be sizing the unit in excess of tank requirements. For sake of dramatic illustration use a 500 watt heater in a 20 gallon tank. The heater will short cycle because its capacity to heat is much greater than the demand.

The result of constant short cycling will be component failure. You may want to "undersize" a heater to prevent short cycling. That is, use two 75 watt heaters when you may want to use one 150 watt heater.

The good news is that you now have redundancy in the event of heater failure. The bad news is that you have overloaded another outlet.

[Smokey]

good advice, Raw...forgot about that, I am still using an old EboJ, 250 Watt. the only one that still works well..and it handles the water pretty well and keeps the temp. constant. finger crossed!!!!

but like some one said , keep the water in motion and don't over-heater-watt the tank,
I've got a digital thermometer, so I always have an idea what the water temperature is and if it fluctuates. pretty even temp. most of the time.

[Sean]

Is there a general rule of thumb when it comes to sizing heaters?

Sean.

[Smokey]

Sean;;
a rule of thumb for heaters;
1- in heated room - ~2.5 watts per gallon of water
2- in unheated room - ~ 5 wattes per gallon
( recommened from Aquarium Atlas #1; Hans Baensch)
With todays heaters, some are very accurate, others are - well lets say - not so accurate.
The idea of running two heaters in a tank is a good idea... if one fails the other will act as a back up..using a digidal thermoneter lets you see exactly what is happening in the tank... temp. wise..the digidal thremos can be bought for $5.00-$60.00.. heck ,I'm using the $7.00 one from HH, and they are as accurate as the $60.00 one's.
I have compared them to a scientific calculated thermoneter and they are right on.
ex. my 258 L unit is at 86.6'F..

see ya later

[Sean]

Cool! Thanks Smokey.