Heaters..... How many watts per gallon?

[dakota9]

I have a 30 cube that's actually 29. something gallons and have about 20lbs of live rock in it. I just bought a 150 watt rena heater.

The instructions read that 20 to 30 gallons requires a 100 watt heater, and 35 to 50 gallons requires a 150 watt heater.

I thought I needed a 150 watter

Think I might fry my fish if I use it?

 

[johnr2604]

I always shoot for around 4 watts a gallon.

 

[drnecropolis]

What I have always heard was take total number of gallons and multiply by 5.. The answer is watts needed..

 

[dakota9]

So, am I headed for a fish fry if I use it? It's a different kinda heater, looking for a pic I can copy and paste

 

[dakota9]

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This unbreakable heater features a temperature warning light and works for fresh and saltwater tanks. A warning light flashes in the event of abnormal temperatures. Wide, accurate temperature range of 69 Deg - 93 Deg F.Rena SmartHeater 50: 20 gallons Rena SmartHeater 100: 35 gallons Rena SmartHeater 150: 50 gallons Rena SmartHeater 200: 70 gallons Rena SmartHeater 300: 90 gallons

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[rasbora]

How would it fry your fish? The heaters turn off when the water hits the temp you have it set at.

Though out of my own paranoia, I tend to use 2 smaller heaters rather than one large heater in my larger tanks. I figure if a heater fails to turn off, it'll take twice as long to fry the tank, giving me more time to notice and remove it.

 

[ichthyoid]

IMO- it will just heat your tank up faster, provided it works correctly, of course. I have seen a lot of people suggest using multiple smaller heaters, so if one goes bad it won't fry your fish as fast. Personally, I think 3 watts per gallon would be adequate, as all any of us want is for it to 'top off' the temperature, in our already heated homes. Of course if you keep the temp really low, or the tank is in an unheated space, then that's another matter.

Think about it this way Dakota, how long would it take a 100 watt light bulb to warm-up your tank (assuming you could place one in the tank safely, of course)? Just in case you have never had the misfortune of touching a 100 watt bulb, I will tell you that they can burn the crap out of your fingers in a second!

 

[dakota9]

You know how it is, paranoia takes over at a time like this. I ran the same heater on a 30 long for quitea while w/o realizing the wattage variance.

It's in there now, let's hope it works....

 

[salt reefer]

i have the rena heater just like that one works great lol. now that i got mh i dont even need a heater lol.

 

[ichthyoid]

FWIW- I thought this made a lot of sense, as it uses the 'offset' from ambient room temp to size the tank heater. Still around 3w/gal though, except for extreme offsets of more than 25 deg.

 

[dakota9]

Actually, the heater is in my sump area, right next to the supply pump. As near perfect an area as I can provide.