Heating requirements for a large tank

On Mon, 14 Nov 2005 21:41:14 -0500, "Bill Stock"
wrote:


"Dick" wrote in message
.. .
On Sun, 13 Nov 2005 21:01:01 -0500, "Bill Stock"
wrote:

I thought there was a thread a while back started by John, who wantedA
recommendations for a heater in a large tank. But I googled and could not
find it.

The tank in question has a radius of 34" and a depth of 24", but I'll
likely
keep the water at 18". This is roughly 200 gallons. I tried a couple of
heater calculators on the web, one said 28W (LOL) and the other said 700W.
I
was hoping for less, but I imagine the 700 is close. Although the same
calculator said I need 300-400 watts of light for my 55 gallon. My poor
Cardinals would need sun glasses. I only want to raise the temp about
5°
F on average.


You don't mention where you keep the tank. If it is a heated area,
you can raise the room temperature close to the desired tank
temperature. During this last summer, I set the room temperature to
77F and let the house A/C keep it there. This winter I will need the
heaters as I plan to keep the house at 72F, natural gas heating costs
versus electric tank heater costs being the consideration.

It's in an unheated entryway in the basement. So the temp will be 55-60 on
most days. Ideally I'd like to keep the fish at 60, but 70 would be better
for the plants. These are Goldfish BTW, so the lower temps are not a
problem. But I prefer 60 to avoid any feeding issues.

Trouble with lights as heaters, what happens when you turn the lights
off? I have a 29 gallon with a fully enclosed hood that tends to
overheat while the lights are on. That is with 40 watts of light in
29 gallons of water.


The light will be suspended at least 2'-3' above the plants to prevent
burning. I don't actually know how much heat they will provide. I'll likely
have to build a cover to hold in the heat.

I don't think I understand your problem. If your room temperature is
70F you need less watts, than if the room temperature is unheated and
tends to vary through out the day. You can have more than one heater
in the tank. Lot's of watts means you can heat faster, fewer watts
means the heating time may be longer and not keep up with the outside
changes if those are large.

So, what is your room temperature like in the winter?

House is 68 daytime and 60 nighttime.



dick



As I see your problem you need to maintain 65 to 70 degrees in a room
that may go to 50F and will be changing through the day. Not having a
top to the tank will allow the air warmed by the water to evaporate
carrying off heat.

I would think of a way to use a light hood that covers the tank top,
first of all.

Then I would plan to have 2 or even 3 heaters, maybe 200 watts each.
I imagine you have power filters, these will help keep the heat
distributed.

I would consider heating the hallway if the doors to it are kept
closed. The presence of the heated tank is going to heat the room
anyway, but if the room is heated then it will keep the tank warm. I
have a 75 gallon tank located near the room thermostat. It drives me
nuts in the summer. I like to cool the room to 76 degrees, but the
tank tells the thermostat the room is 78, so the A/C comes on and the
room sinks to less than 76 wasting energy and making the rooms
uncomfortable, so I end up raising the thermostat to 78 to shut off
the A/C. I learned to live with 78 degree room temperatures last
summer.

dick