Is there a such a thing as too much heater capacity?

[yhbae]

Following the general rule of using 50w per 10 gal - for 25g, I need to use 125w. The kit I bought came with 100w which isn't enough but since it is summer right now, the water temperature seems pretty sturdy.

Since I live in Montreal, it gets cold here during the winter. Even worse, in order to save electricity cost (despite having the lowest rate in North America :) ) I don't keep heating on in all rooms. The living room where the fish tank is located, will be set at 10C over nights, and during some nights, I've seen it approach that. (The temperature doesn't usually dip below 14C.) So my plan was to add a second heater, perhaps around 150w.

Would this be enough? What if I go for 250w instead (since it only costs about $3 more? I'm looking at those Ebo Jager ones) Will I fry the fishes near the heater if I do this?

Appreciate any feedback.

[ChilDawg]

You always, always want to use undersized heaters, so that, if they fry, they won't fry the fish before you notice. Also, it seems to work best to use two on larger tanks so that, if one gets stuck switched on, the other one will shut off...and you won't fry the fish before you notice.

[ChilDawg]

BTW, I've heard the rule is 2.5W/gallon, not 5W/gallon for the reasons stated above.

[wetmanNY]

' An old-fashioned rule of thumb was, two watts to raise each gallon five degrees above the ambient room temperature. So a ten-gallon tank kept at 75oF in a room that was 70o would need a 20-watt heater.'

-quoted from www.skepticalaquarist.com so that if it's egregiously wrong, I can edit it.

[ChilDawg]

I think that I can buy that, WetmanNY...and it seems to jive with the recommendations normally given, as I'm guessing that they assume the "standard" room temperatures of 68F in the winter and 78F in the summer...

Eheim makes the recommendation of 0.5-1W/L which is between a little under 2 and a little under 4 in terms of Watts/gallon.

Here's the site: http://www.eheim.com/technik_heizung.htm

[yhbae]

Originally posted by wetmanNY
' An old-fashioned rule of thumb was, two watts to raise each gallon five degrees above the ambient room temperature. So a ten-gallon tank kept at 75oF in a room that was 70o would need a 20-watt heater.'

-quoted from www.skepticalaquarist.com so that if it's egregiously wrong, I can edit it.

In the worst case scenario, my living room temperature in the winter could approach 50F and I want the water temp to be 77F minimum - this is 27F difference.

So: (27/5) * 2 * 25 = 270w!

The above says I need 270w power to keep my 25g at normal temperature... This means my original idea of having two heaters (100w + 150w) is still not enough...

Am I mistaken?

[ChilDawg]

It's a good idea to do maybe 3 90W heaters because that will make it easier to keep the fish from being boiled in the summer...Your calculations are correct, by the way.

[yhbae]

Thank you for the confirmation that the calculation is correct - at least now I know... :)

Since I haven't seen 90w heater before, I guess I should buy two more 100w heaters?

Another question - I've heard that weaker heaters are generally less reliable than stronger ones and are less capable of holding temperatures steady... Myth?

Appreciate any feedback... :D

[ChilDawg]

Truth...to a point. It is a good idea to have enough wattage to keep the tank at the right temp...

I think, though, that buying quality is better than buying cheap heaters...and buying 3 100s of good quality is your best bet. I'd recommend that, yes.

[yhbae]

Great! I guess I'll go ahead and order some Ebo Jagers (I assume they are good quality heaters?) for both my community tank and other tanks (using the same formula)...

Thanks for the help! :D

[ChilDawg]

No prob...

They're high-quality heaters...they've lasted 20-30 years for some of our members...check out the thread "Goodby old friend" in Freshwater DIY to see that!