Heater needs...

[Mugwump]

I was rumbling around checking some of the various heaters available now days, and found this...

"As for heating requirements, I recommend 25 watts of heater for every 10 degrees of ambient temperature per 10 gallons you need to raise your aquarium temperature.
EXAMPLE: If your home is 68 degrees and you have a 40 gallon aquarium, to reach a temperature of 78 degrees you would need a 100 watt heater."

I thought about it, and I think that this might be one of the simplest gauges of needed tank heater wattage that I've seen before....

your thoughts?....

the rest of the article.....and link for much more... http://www.aquarium-pond-answers.com/2007/01/aquarium-heaters-preset-vs-non-preset.html
....................

Often when heater problems occur it is due to the heater being of the improper wattage to meet heating requirements of an aquarium in the location it occupies. Too high a wattage can result in rapid temperature rises that can result in cooked fish if you make adjustment mistakes.

The above formula is a VERY accurate guide and I have used this formula for many years with no issues of under or over heating. In fact I have often witnessed less than honest retailers tell a customer that (for example) they need two 300 watt heaters for their 125 gallon aquarium when in reality ONLY ONE is required for the average room that is kept at 68 degrees during the cooler hours (usually at night while asleep).
So PLEASE be careful with stores or web sites that try and over sell you as to your heater needs.

Also, if your room is warm (such as in summer months) you may end up with aquarium temperatures higher than your settings (example: a room that is 85 will keep an aquarium at 85 even if your heater is set at 78 F).

It is important of all heaters, regardless of type to maintain good circulation around the heater for the best results for temperature control and accuracy. I have used (& even designed my own) heater modules for in-line heater applications and I will be the first to admit these do not properly dissipate the heat, especially with titanium heaters.
Even though I really like the durability of Titanium Heaters, these types of submersible aquarium heater are best used inside the main display aquarium where the heat will dissipate more rapidly than in a sump or similar enclosed space. I have witnessed Titanium Heaters (of different brands) over heat and burn out when used in small sumps or heater modules. I recommend using a glass or quartz submersible heater in sumps or similar as glass submersible heaters do not seem to be as sensitive to this problem.

Another point is often when the ambient temperature is more than 25? F (14? C) under the desired temperature, the use of two appropriately sized* heaters often works better from my experience.
*By appropriately sized, I mean using the above cited formula.

As well, on the "top end", aquarium heaters are designed only for a top temperature of 90? to 95?F (32? to 35?C), so attempting to heat any higher will likely result in failure and even damage to the to heater.

[BillT]

Geeking out here:

It may well be a reasonably useful formula, however it is a simplified formula for dealing with heaters and tank temperature.
Therefore I don't really like the VERY ACCURATE part.

Water to Heat:
The factors involved would be the amount of water to heat and therefore the amount of heat needed to increase it temperature.
That would be the number of gallons. Makes sense.

Heat Losses:
There is also the surface areas through which heat would be lost. Bottom, sides, and top. If the bottom or side were insulated (styrofoam) than they should be treated separately. A cover on the tank will provide some insulation and will reduce evaporation (which also uses heat from the tank to evaporate the water). Evaporation would be increased by the flow of air out of the enclosed tank if it is aerated.
These are the ongoing heat losses that the heater would be working against to increase the temperature of the tank.

Presumably these are factored in in some way as a standard tank dimension, but the important thing is the ratio of surface area to tank volume. These are not the same as a tank of a given shape is increased, the volume will grow as a third power of a linear dimension (such as length) while the surface area will grow as a square of a linear dimension. Generally large tanks will have more volume compared to their surface area than smaller ones. In addition, some tanks have weird shapes (like shallow breeder tanks) which will be further off from "normal" and have more or less surface area than a differently shaped tank might have.

Temperature Difference:
The temperature difference between the room in which the tank is located and the desired tank temperature is the force driving the heat being lost out of the tank, so that part makes sense.

I would say a very accurate formula would take these things into account.


His water circulation points are good, but I don't understand how an in-line heater doesn't work well unless the circulation through the in-line system is not sufficient, which is the same problem as poor water circulation in the tank.


I have never had a problem with titanium heaters which I have had several in sumps and even a couple in rather high temperature small volume water baths (over 100˚F, set-up for lab use).

He did not address having a thermostat separate from the heater. This is something I like a lot but is not often an easy option anymore. Requires good circulation to work as well.

[Mugwump]

I think his answers are aimed more for a hobbyists general conditions.....and not specific in nature by any means....but they are well written and understandable....and, yes, there will always be variables..

[b125killer]

My saltwater tank is 40g it has two 150w heaters in it. one is set to 78 the other is set to 80. I haven't worried about over heating the tank. I like to use the two heaters not because one heater wouldn't work. but because one heater might fail on me.
the discus tank has two 300w heaters. There both set to 86 degrees. I'm not sure one heater will heat the tank that high. I did this one so that one heater won't be overworked.
I think as far as a hobbyist goes, they want to be told that this heater will work or won't and why it won't. There not going to sit down and figure out the math to see what heater they need.

[BillT]

I agree. I just don't like VERY accurate when its not VERY accurate (words matter to me).

I don't do calculations because too many uncontrolled variables and questionable heaters.

Mostly, I stick a heater in a tank (hopefully in the right size range), dial in a high set point and check the tank temperature periodically till I can tell how its doing.
I no longer trust any of the settings on heaters so I wait for the temperature to go up to the temp I want, and then dial back the heater until it just turns off. This sets the set point so it should turn off when the tank is at temp. (A possible problem is when the heater is going all the time to just maintain the temperature. If the room temp goes up, say in summer, then you might end up with a too hot tank.)
Then I watch it for a day or two to see how well it maintains the temp.
If it does not get high enough, I add a second heater or further adjust the first one or change the water flow around it.

[LizStreithorst]

The only way to do it right is to have heater controllers.  If I knew more stuff I could make them myself for way less than they cost to purchase.  The same is true of LED lights.  I can't do either myself and I'm too cheap to spend my money on them.

[Mugwump]

..and I agree.....the heaters now days aren't that reliable...I'm always checking mine, I just don't trust them too much....

If you'll not in his text he continually says that heater settings are unreliable and to continue to check them and adjust as necessary for desired temps.....

I think he uses 'very accurate' as to state a heater wattage needed per gallons of water as a reference, and yes, in a perfect world it's damn close...I get the feeling that it's really about 'not' over heating a tank unnecessarily.. the folks seeking his info are not likely to be seasoned hobbyists...

[Mugwump]

The only way to do it right is to have heater controllers.  If I knew more stuff I could make them myself for way less than they cost to purchase.  The same is true of LED lights.  I can't do either myself and I'm too cheap to spend my money on them.

LED lights are too much hassle to make when the prices are now reasonable and getting cheaper all the time.....controllers are only as good as the heater that is used....

[LizStreithorst]

I need to look again at LED's.  It's just that I have so many tanks...Controllers won't keep a heater to conk out and not turn on.  Fish can take a bit of a chill.  They can save you if a heater sticks on. 

[BillT]

I like good controllers a lot.
Using a garden variety aquarium heater and a really good controller (~$300) (along with a small powerhead (for circulation) and a styrofoam cooler) I have made research lab water bath that kept the water within 0.1˚C of the set point.

A really nice controller will also allow you to plug it into a monitoring system which could call you up if the temp does not hit the set-point within some period of time.

[b125killer]

When I get my big saltwater going I'll do a controller on it. It's too important on saltwater. It can't handle temperature swings like freshwater. I'll still use two 300w heaters in the sump. It's a bigger water volume then the discus but I think 300w heaters should be fine. Still it's a guess I won't know for sure until I try it.
As far as the led lights Jon is right. They are dirt cheap now.