75 gallon tank, should I use 1 or 2 heaters? Question 

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ruthven78

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Should I use just one 300w heater or two smaller wattage heaters? Room temp can range from 67-70 degrees. Im not entirely sure what I want to put in my tank yet. I would like to keep the heat at around 75-77 deg. I was thinking of getting Marineland Stealth or Penn-Plax Guardian
 

David C

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A lot of people use two heaters for the dependability, if one goes out you always have a backup in the tank. For a tank that size I would recommend it, the stealth pro heaters are really nice since they added indicator lights to them.

Dave
 
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ruthven78

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so would two 200w heaters be good?
 

Goldwing_Don

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yes 2 2oo watt heaters would do it
 

Jaysee

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ruthven78 said:
so would two 200w heaters be good?
Yes. You can't have too strong of a heater. The higher powered heater won't work as hard to maintain temp, whereas an underpowered heater will be constantly running and may never reach temp.
 

btate617

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I disagree and I will explain why.

For me I always go with a heater on the smaller side. A few reasons for this. First I don't mind paying the extra few cents it cost for it to run a bit longer than a stronger heater. Second too many times you hear my heater malfunctioned and stuck on and fried my fish. A stronger heater will heat a tank a lot faster if it sticks in the on position than a lower watt one will, simple. Yes it can happen to either but with a smaller heater you have more time to catch it as it will take the smaller heater longer to heat the water to a temp the fish can no longer handle. Many people will say with todays heaters this no longer and or very rarely happens, but it does.

Just my opinion.


Brian
 

Jaysee

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IMO an underpowered heater has a higher chance of malfunctioning, because it's doing a job that is bigger than it was designed to do. Things have a habbit of breaking when they are pushed to the limits, IME.

From what I've seen, a heater getting stuck on and cooking the fish is incredibly rare...can't say I've ever heard of it ACTUALLY happening, but it is something I've heard people worry about.
 

btate617

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I agree with what you are saying, I get it.

However how many times have you heard my 200W heater malfunctioned and fried the fish in my 90gal? Unless you don't go in the fish room but everyother day you will catch a smaller heater problem before you lose everything.


Brian
 

Jaysee

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I editted my previous post.

An underpowered heater that burnt out and has stopped working will kill the fish just as readily as an overpowered one getting stuck on and cooking the fish. Again, I think the former is much more likely than the latter.

My stealths have never let me down or cooked a tank, but I have had heaters of lesser quality stop working and the fish died.
 
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ruthven78

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I always just seem to have heaters that break but never any that have killed the fish. Which is why Im going stealth (or guardian)
 

Jaysee

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I've got a box full of heaters, and 14 stealths in operation.
 

btate617

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Yes but an under powered heater that fails will take a long time to "cool" the fish to death.
Again you would have to be someone who checks on your fish everyother day for this to happen.

Water that has no heater, sitting at room temp, will be around 4-5 degrees cooler than the airtemp.

So lets say you keep your house at 72degrees in the winter (72degrees bacause thats what mine is at in winter so the kids and wife don't complain lol) and your tank at 78degrees. If you heater fails, fails to come on, first it will take quite some time for it to cool just to room temp (72degrees). And even longer to drop the extra 4-5degrees. I would say minimum half day to go from 78degrees to 67-68degrees, probably longer. (of course this depends on tank size with a smaller tank it will happen quicker than on a bigger tank in the same room).

What is rec. for a 55gallon normally? 250W? It won't take long on full power to heat that tank to above a level that kills fish.


My main point is you have a better chance to catch a problem with a lower watt heater.
Also how many times have you heard someone say oh no my heater stopped working and my fish froze. Not very often, me myself never. You would have to ignore your tank for a long period to have this happen. However I have read/heard many say man I cooked my fish.


One other thing I see your point about the longer a small heater runs the better chance it has of failing. However these things are made to run. I am not being a wise guy, but do any boxes these days say this heater should only run for set amount of hours? (I haven't bought a heater in a box in a looooong time) They are designed to run, not for a set period of time, but on and off as needed until the set temp is satisfied.



Brian
 

btate617

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Jaysee said:
From what I've seen, a heater getting stuck on and cooking the fish is incredibly rare...can't say I've ever heard of it ACTUALLY happening, but it is something I've heard people worry about.

I the past 10 years I know personally probably 5 or 6 people who it has happened to.

Check some other forums, search it maybe, it isnt an everyday occurancy, but it happens.


Brian
 

Jaysee

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I keep my house at 68 to avoid massive gas bills. One thing though - the wattage of the heater is a function of the difference in ambient air temp and water temp, as well as tank size.

p.s. - excellent discusion
 

btate617

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Jaysee said:
I keep my house at 68 to avoid massive gas bills. One thing though - the wattage of the heater is a function of the difference in ambient air temp and water temp, as well as tank size.

p.s. - excellent discusion

Exactly thats why I said longer to heat up a big tank compared to a smaller one, or did i say a small one will cool faster than a big one....not sure it is late.


One thing though - the wattage of the heater is a function of the difference in ambient air temp and water temp, as well as tank size.

If you have a submersible heater then does ambient air temp go out the window, and only water temp and tank size come into play?

p.s. - excellent discusion
Yep I agree, I have learned more this way than any other.


Brian

If i kept the house at 68 I would get kicked out.......
 

Jaysee

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The smaller the tank, the faster the temp changes.

Heat is always transferred from hot to cold, until equilibrium is reached. Work must be done to maintain that difference. How much work (heater wattage)is a factor of several things, including the temp difference desired, surface area, volume and material.

The material between the two (air and water in this case) determines how quickly that heat exchange occurs. As far as materials (non-metal) are concerned, glass is a pretty good conductor, meaning a faster heat exchange.

Heat is transferred from the water to the air through the surface area, and a smaller tank has a higher percentage of it's volume in contact with the conductor (glass), so it loses heat faster.

The larger the temp difference, the faster the exchange, so it would take more work to maintain a 20 degree difference than it would a 10 degree difference.

I can't for the life of me remember the formulas...we were always allowed to use a formula cheat sheet.

That's the physics of it...
 

Aquarist

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Good morning,

I like the Stealth Pro heaters too. I have 3 250w in my 265g tank. The indicator lights give me peace of mind. They shine green when the selected temperature has been reached and they glow red when the heater is actually heating. Very accurate within 1 degree. By having 2 heaters in your 75 gallon tank will help to eliminate cold spots. I recommend you place them horizontally in your tank, a couple inches away from the bottom. If possible place them under the out flow of your hang on back (HOB) filter/filters. The will help to distribute the heat more evenly through the tank. Place 1 on each side of the tank.
Ken
 

David C

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Maybe I'm crazy, but I use the RKL to control my 2 heaters and then have the thermostats on the heaters set a little higher. If for some reason the controller fails and sticks on, then the heaters will still have their own independent thermostats to count on. I would be in trouble if the controller failed and didn't turn them on at all, but I check my tank temps at least 3 times a day so I'm good there I think.

Dave
 
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ruthven78

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just my luck, I saw a cheaper Fluvall m300 heater, 300w, and decided to buy it since I got it for $24.99 at my LFS. It even said "submersible" on it...so I thought that meant you could put the entire thing in the water.....so such luck, on the inside it says "for the north american version do not run with water above the max fill line."......so do I keep it or take it back? Petsmart wanted $40 for the Marineland Stealth 250w. Right now I can only really afford to get one heater.

I kinda wanted a heater that could be fully submersed so that it would be parrelel to the glass, or one I could lay sideways.
 

David C

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I would go with the stealth, they are extremely dependable heaters and you won't regret it several years from now, plus they're "unbreakable"... still possible to break but much sturdier than a glass heater.

Dave
 
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