Cant get my temp up - - Tropical Fish Keeping - Aquarium fish care and resources
Old 12-25-2013, 07:54 AM Thread Starter
Member

Cant get my temp up -

I have 2 300W Fluval heaters in my sump and they are set to the max setting and the temp will not go above 80.

I have a 180 gallon tank and the sump is a 30 gallon long.

I unfortunately brought home some ich from a pet store that I will never shop at again.

Gave up on the salt and temp and had to add cupramin a few days ago.

How many 300W heaters do I need to get better temp control?
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Old 12-28-2013, 02:49 AM
New Member

How long did you wait for a temperature rise? It takes about 9000 joules of energy to increase 1 gallon of water 1 degree F. 600 watts delivers 600 joules per second. For 1 gallon to increase 1 degree F you need 15 seconds. With a 180 gallon tank plus a 30 gallon sump, you are looking at about 1 hour to increase 1 degree F. Once you get a few degrees above room temperature, you start to lose some of the energy from the tank to the room, and it will take even longer for the temp to increase. As the temperature difference continues to increase, so does the amount of heat loss to the room. Eventually you will reach a temperature where the heat loss equals the 600 watts your heaters are generating and your water temperature will no longer increase.

I'm running 200 watts on a a 46 gallon tank. The temp is set to heat the water 10 degrees F above room temperature, and the heater is only on about 30% of the time. I have a glass tank with a glass cover. Open tops would lose more heat, and acrylic is a better insulator. I would think 600 watts would be enough if the heaters were in any kind of water flow in the sump.
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Old 12-28-2013, 06:42 AM Thread Starter
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Quote:
Originally Posted by Electric View Post
How long did you wait for a temperature rise? It takes about 9000 joules of energy to increase 1 gallon of water 1 degree F. 600 watts delivers 600 joules per second. For 1 gallon to increase 1 degree F you need 15 seconds. With a 180 gallon tank plus a 30 gallon sump, you are looking at about 1 hour to increase 1 degree F. Once you get a few degrees above room temperature, you start to lose some of the energy from the tank to the room, and it will take even longer for the temp to increase. As the temperature difference continues to increase, so does the amount of heat loss to the room. Eventually you will reach a temperature where the heat loss equals the 600 watts your heaters are generating and your water temperature will no longer increase.

I'm running 200 watts on a a 46 gallon tank. The temp is set to heat the water 10 degrees F above room temperature, and the heater is only on about 30% of the time. I have a glass tank with a glass cover. Open tops would lose more heat, and acrylic is a better insulator. I would think 600 watts would be enough if the heaters were in any kind of water flow in the sump.
It's been over a week - I'm maxed out at 82 degrees even with the 2 300 watt heaters at the highest setting.
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Old 12-29-2013, 03:56 AM
New Member

What is your room temperature? Assuming it is 68 degrees, then you need another 170 watts to get to 86 degrees. Or you could try to insulate the tank a bit.
Electric is offline
Old 12-29-2013, 09:19 AM Thread Starter
Member

Quote:
Originally Posted by Electric View Post
What is your room temperature? Assuming it is 68 degrees, then you need another 170 watts to get to 86 degrees. Or you could try to insulate the tank a bit.
so maybe a 3rd 300 Watt heater will work?
steelersx is offline
Old 12-29-2013, 09:40 AM
TFK Moderator

When I had a 180g tank with a sump I had 2 x500w, one rule that does work for large tanks is about 5w of heat per gallon of water.

Having a top also helps keep the temperature in the tank up as mentioned, as you lose less heat to the room.

With ich it is particularly important to get the temperature up to speed up the lifecycle and cause minimum effect.

Good luck and hope it works out for you.

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Old 12-29-2013, 09:40 AM
Member

Great explanation given by electric!

Quote:
Originally Posted by steelersx View Post
so maybe a 3rd 300 Watt heater will work?
If 2 doesn't get the job done then yes get a third. Like was said, the greater the difference between the air and desired water temp, the more power is required to achieve that temp.

Do you have glass tops? They do an excellent job retaining the heat.

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Old 12-29-2013, 10:46 AM Thread Starter
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Quote:
Originally Posted by jaysee View Post
Great explanation given by electric!

If 2 doesn't get the job done then yes get a third. Like was said, the greater the difference between the air and desired water temp, the more power is required to achieve that temp.

Do you have glass tops? They do an excellent job retaining the heat.

Yup have glass tops.
guess I'll get a 3rd 300 watt
No signs of ich spots for at least 5 days now so hopefully the meds are doing the job.
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