Go Back   Aquarium Advice - Aquarium Forum Community > Saltwater and Reef > Saltwater Reef Aquaria
Click Here to Login

Join Aquarium Advice Today
Reply
 
Thread Tools Search this Thread Display Modes
Please support our sponsors and let them know you heard about them on AquariumAdvice.com
 
Old 04-06-2007, 02:48 PM   #11
AA Team Emeritus
 
roka64's Avatar
 
Join Date: Mar 2006
Posts: 13,860
Send a message via AIM to roka64 Send a message via Yahoo to roka64
Quote:
Originally Posted by Kurt_Nelson
Can you tell I'm still not convinced!
LOL! Ok, say your lights cause the tank to heat up to 80. Set the heater to 80. When the lights are on, the heaters shouldn't really be coming on very much, since the lights are heating the water...right? Now, when the lights go out, the temp will start dropping, causing your heaters to come on to compensate for the loss of heat, from the lights....Does that help any?
In a straight forward way (not talking about accuracy or the ranges of heaters) the heater should run less while the lights are on and more when they are out. This isn't taking into account room temp, phs or any other temp effecting variables.
__________________

__________________
Age is relative, you are only as old as you act....of course, this works in reverse....

Questions loved, heeded advice greatly appreciated!

Vote for AA
Good reading about:
Nitrogen Cycle
Fishless Cycling
Need more help?
Articles
Acronym List

--Scott
roka64 is offline   Reply With Quote
Old 04-06-2007, 02:56 PM   #12
Aquarium Advice Addict
 
Join Date: Aug 2006
Location: not here anymore
Posts: 5,338
OK... My heaters are normally set at 78 but my tank increases to 80 at the end of the day. I set my heater to 80. My house is 70, so at night after the lights go out, the tank temp wants to go down. My heaters kick on and keep the tank at 80 all through the night. Next morning - before the lights kick in, my tank is at 80. Now here's where we differ in opinion...

My lights come on, start pumping heat into my water. What I'm saying is that by the end of the day - with lights blazing away - my tank is still not going to be at 80! It's going to be at 82 - even without the heaters ever coming on during the day.

I should also point out that I'm assuming my room temp is always below my tank temp in my argument.

The more I type, the more I'm convinced I'm right! Anyone with a degree in thermodynamics out there? I studied it in school, but that was a few brain cells ago!
__________________

__________________
Kurt_Nelson is offline   Reply With Quote
Old 04-06-2007, 03:05 PM   #13
AA Team Emeritus
 
roka64's Avatar
 
Join Date: Mar 2006
Posts: 13,860
Send a message via AIM to roka64 Send a message via Yahoo to roka64
Where do you have your thermometer?
__________________
Age is relative, you are only as old as you act....of course, this works in reverse....

Questions loved, heeded advice greatly appreciated!

Vote for AA
Good reading about:
Nitrogen Cycle
Fishless Cycling
Need more help?
Articles
Acronym List

--Scott
roka64 is offline   Reply With Quote
Old 04-06-2007, 04:22 PM   #14
Aquarium Advice Addict
 
Join Date: Aug 2006
Location: not here anymore
Posts: 5,338
Quote:
Originally Posted by roka64
Where do you have your thermometer?


It was a hypothetical situation... sorry!

Personally... I have my heaters (2x) set so they keep the water at about 77 degrees, plus/minus 0.5 degrees. During the winter, my room temp is stable during the day at 70 degrees. During the winter, my tank normally starts the day in mid 76 area - and ends the day in the high 77s, sometimes in the low 78s when my room temperature gets much above 73 degrees. (Oh... and my thermometer probe is against the back wall, about 2/3 the depth of my tank, in between my two heaters. It's not near any powerheads or other heat sources.)

During the summer... well, I'm not sure yet, as my tank was only started in September of last year! But with our warmer temps as of late here in WA (todays it's in the mid 70's... woo hoo!), my room temps have started creeping up a little, and I've noticed my tank temps at the end of the day have also started creeping up. And that makes sense because there is less of a temperature differential between my tank water and the room... therefore the heat loss to the room from the water is slower.
__________________
Kurt_Nelson is offline   Reply With Quote
Old 04-06-2007, 04:59 PM   #15
AA Team Emeritus
 
roka64's Avatar
 
Join Date: Mar 2006
Posts: 13,860
Send a message via AIM to roka64 Send a message via Yahoo to roka64
Quote:
Originally Posted by Kurt_Nelson
And that makes sense because there is less of a temperature differential between my tank water and the room... therefore the heat loss to the room from the water is slower.
This sounds like it answers your question....The heaters are trying to keep up at night, once the lights come on, the temp of the tank is still high (say 80) and your lights heat it even more, for a period of time, until the tank stabalizes...Does that sound better..? LOL!
__________________
Age is relative, you are only as old as you act....of course, this works in reverse....

Questions loved, heeded advice greatly appreciated!

Vote for AA
Good reading about:
Nitrogen Cycle
Fishless Cycling
Need more help?
Articles
Acronym List

--Scott
roka64 is offline   Reply With Quote
Old 04-06-2007, 06:15 PM   #16
AA Team Emeritus
 
Join Date: Sep 2005
Location: VA
Posts: 3,391
Send a message via Yahoo to tecwzrd
IME it doesn't work that way unless the room temperature is unusually high.

Think of it this way.

Before you had your heater set at 78 and your lights caused the water to warm to 80 at the end of the day in a room of 70 degrees. Your heater wasn't on constantly during the day and the lights at some point took over the heating of the tank to the "max temp" of 80.

Now consider it's set at 80 degrees and again if your lights previously heated the water from 78 to 80 degrees (max) in the same 70 degree room then when the lights come on the heater would therefor would turn off and not come on at all since the water is already at the maximum temperature that the lights can heat it with the heat transfer from the tank and the room temperature as a constant.

The lights can't heat it beyond it's previous "max temp" unless the room temperature is higher which through heat transfer of the tank would keep it at it's "max temp".

If your logic proved true then theoretically the lights had the power to heat it beyond the 80 degrees regardless which could also be true if enough time had not lapsed to fully reach the "max temp" i.e. tank was at 73 degrees and lights heated it to 78 but that still wasn't the "max temp" of 80.

The point is to avoid wild fluctuations in temperature but still keep the tank in the desirable range of temperature.

Fluctuations in both the ambient room temperature and the quality of heaters thermostat are both going to give you mild differences in overall tank temperature regardless but still within the acceptable 2-3 degree range.
__________________
-Micah-

If you haven't figured it out yet I like to BOLD links :P

Vote for AA at Aqua Rank
tecwzrd is offline   Reply With Quote
Old 04-06-2007, 06:26 PM   #17
Aquarium Advice Addict
 
Join Date: Aug 2006
Location: not here anymore
Posts: 5,338
While the internet is good for a lot of things, debating is not one of them!

I'll have to go off and ponder your comments, tecwzrd. I think my reluctance to accept it stems around your statement...

Quote:
...since the water is already at the maximum temperature that the lights can heat it...
There seems to be this concept that the lights will heat the water to a distinct temperature, regardless of the original water temperature. By that logic, if you're above that distinct temperature to start with, then the lights won't heat the water at all. That just doesn't seem right to me.
__________________
Kurt_Nelson is offline   Reply With Quote
Old 04-06-2007, 07:01 PM   #18
Aquarium Advice Activist
 
Join Date: Jan 2007
Posts: 103
Kurt, I am with you, I thnk we are arguing the same poin differently. It happen in my tank. My lights and the tempeture under my hood( before I added the fan )was way over 90 degrees. no way to set a heater at the high point because it was just way to high with the heat coming from the heater and the lights. Whereever the heater was set the lights just made it ge even hotter during lights on time. I am adding a refugium this weekend whch I believe will help even more, there will be more water volume not directly under my strong lights. I would imagne all this depends on depth, fuge, and type of top my is the enclosed wood type and held the heat before fan.

But to answer the original post , I would add a fan not up your heater.
__________________
produceb is offline   Reply With Quote
Old 04-06-2007, 09:14 PM   #19
Aquarium Advice Addict
 
Join Date: Aug 2006
Location: not here anymore
Posts: 5,338
I'm still pondering your comments tecwzrd... but I thought I'd answer this in the mean time...

Quote:
If your logic proved true then theoretically the lights had the power to heat it beyond the 80 degrees...
Yes... assuming you started at a higher temperature. My thinking is that if you start at 88 degrees, you're going to end up with 90.

Quote:
...regardless which could also be true if enough time had not lapsed to fully reach the "max temp" i.e. tank was at 73 degrees and lights heated it to 78 but that still wasn't the "max temp" of 80.
Not really... if the tank started in the morning at 73 degrees, given the same conditions you'd only be at 75 when your lights went out. It's that 2 degree difference - regardless of starting temp.

I'm not questioning at all that stable temps are key - regardless of the actual temperature. I'm just thinking that cranking up the heater is not the key to stable temps.

The more I think about it, the thing I'm ignoring in my previous discussions is heat flow OUT of the tank, and maybe that's where things get fuzzy. Heat flow OUT is definitely dependent on the temperature difference between the tank and the room. If you increase the tank temperature, you're increasing that temperature difference, and you effectively get more heat flowing out of the tank. The larger temperature differential drives more heat "current" out of the tank.

Perhaps this larger heat flow drives more heat out of the tank, thus equating to a smaller temperature increase between morning and night. But without being familiar with the heat transfer coefficients for that aspect of things, I'm having a hard time believing that a couple degrees difference in tank temperature could increase the heat flow out of the tank by that much.


Edit at 7:00pm PST:

OK... how's this:

SCENARIO #1: Let's say you've got a 10 degree difference between your tank and room. That would give you a set amount of heat transfer from the tank to the room, thus dropping the temperature of the tank. In this scenario, a percentage of the heat you add to the tank gets taken out by this differential heat transfer.

SCENARIO #2: Now let's say you've got ZERO degree difference between your tank and room. You would have NO heat transfer from the tank to the room. Any heat that you add to the tank, stays in the tank.

In both scenarios, the tank is at the same temperature. BUT, in scenario #2 the tank will increase in temperature MORE than in scenario #1 - but only because there is no heat loss in scenario #2. In both cases, the lights are putting the same amount of heat/energy into the tank. It's just that scenario #1 allows you tank to rid itself of some of it, instead of increasing the temp of the tank.

If you raise your tank temperature in scenario #2 so that you have some amount of temperature differential, instead of ZERO... then you would end up with some heat loss to the room. And that would allow your tank to not increase in temp as much as it did before. It's not that the water has some ability to accept less heat from the lights... it's just that it's getting rid of some of that heat now and giving you a lower temperature.

Sorry for the rambling dissertation, but after rereading some heat transfer text books (yuck) I think this could be what's going on. It actually makes sense of both what I'm trying to say, and what others obviously have observed - higher water temp makes less of a temp change.

Even if true, I don't think it means the "set the heater at the high temp" rule is a hard and fast rule. I think it all depends on the temp differential between your tank and room. For some people, it might work. For others, it would just keep elevating the tank temp.

OK... I'll stop beating the horse for a while. I'm sure it's close to dead!
__________________
Kurt_Nelson is offline   Reply With Quote
Old 04-07-2007, 12:16 AM   #20
Aquarium Advice Activist
 
Join Date: Jan 2007
Posts: 103
x= tank size
y = heat dfferential
z= temp loss


x2-67y/2 *36= z

just kidding wanted to make sure the horse was dead
__________________

__________________
produceb is offline   Reply With Quote
Reply

Tags
eat, heat, light, lighting

Please support our sponsors and let them know you heard about them on AquariumAdvice.com

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lighting causing excessive heat bpeitzke Saltwater Fish Only & FOWLR 13 01-17-2008 02:08 PM
MH Lighting 4" over 75g tank - HEAT?? john0087 Saltwater & Reef - Getting Started 4 07-20-2006 01:57 AM
lighting heat question? 2revup Saltwater Reef Aquaria 15 05-04-2006 02:25 AM
Excessive heat from lighting Reese General Hardware/Equipment Discussion 3 02-25-2006 06:06 AM
MH lighting and heat generated david_396 General Hardware/Equipment Discussion 8 11-17-2005 03:24 AM







» Photo Contest Winners








Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -4. The time now is 12:10 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.