maintaining regular temperature?

[farnorth]

I have a 90 gallon tank with a 30 gal sump. I have one 300 watt heater on the tank and a 48" aqualight pro. I leave my lights on for about 8 hours a day and then my temp goes up from 77-80 every day, then back to 77. With the lid on it fluctuates by about another degree. Any ideas how to help regulate my temp? Would another heater help or make it worse? I am stuck.

 

[sepulatian]

Yes, add another heater to the other side of the tank. 300 watts realy isn't enough for a 90 gallon tank.

 

[farnorth]

Thanks... I assumed that I should, but did not know if it would just raise the temp overall and cause me more of a problem.

 

[lion_crazz]

Do you have a fan blowing on this tank or at the lights at all?

 

[beth]

Put one heater in tank, and another in the sump.

 

[renogaw]

is a 2 or 3 degree swing a major issue? mine does that in my 75 and i never thought about it.

 

[lion_crazz]

Maybe I am missing something here, but why is everyone recommending another heater? This person is having a heat issue. It seems like if anything, he wants to keep the lights from heating his water to 80 degrees. Adding a heater will not stop that...

 

[renogaw]

Originally Posted by lion_crazz
Maybe I am missing something here, but why is everyone recommending another heater? This person is having a heat issue. It seems like if anything, he wants to keep the lights from heating his water to 80 degrees. Adding a heater will not stop that...
that's what i'm reading too... i think he's asking about a cooling issue, not a heating issue. but i'd think such a swing isn't that big of a deal though.

 

[sepulatian]

no, he is saying his temp goes down when he turns the lights off. I took that to mean that his one heater is not holding the temp up when the lights go off. The lights are adding enough heat to keep it up, then when they are off the temp drops. Maybe I am just reading this wrong.

 

[zman1]

Originally Posted by sepulatian
no, he is saying his temp goes down when he turns the lights off. I took that to mean that his one heater is not holding the temp up when the lights go off. The lights are adding enough heat to keep it up, then when they are off the temp drops. Maybe I am just reading this wrong.
That's the way I read what the actual problem to be.
It will be easier to raise the temp during light off hours than to cool it to 77 during light hours. Raise the temp so it maintains a close to 80 24/7. The best I can get is a 1 degree diff at times.

 

[renogaw]

i guess the answer is going to be generated by this question:
what temperature do you have your heater set to?

 

[beth]

Originally Posted by sepulatian
no, he is saying his temp goes down when he turns the lights off. I took that to mean that his one heater is not holding the temp up when the lights go off. The lights are adding enough heat to keep it up, then when they are off the temp drops. Maybe I am just reading this wrong.
Yep. The issue is not heat, but, rather, fluctuation. Fluctuating temps can create a stress issue. It is best to hold the temperature at 80, rather than having daily fluctuations between 77 and 80.
If the max temp is 80 due to light heat, then the heater needs to maintain that 80 degree temperature while lights are off. A single heater is not cutting it, because there are actually 2 systems in this setup: a sump and a display.

 

[renogaw]

if he sets his water to 80, won't that just give the lights a higher base temp to start with? meaning if its at 80, wont it run the temp up to 83?

 

[zman1]

There is potencial it could raise the high end a little. It's a balacing act and you can do better than 3 degrees. However, the question would be how long does it take with lights from 77 to reach 80 and once it's there how long is it at that temp. If that's rising the first 2 hours and stays at 80 for 6 hours. I don't think it would be an issue.
That becomes an issue for me in the summer. I keep the house at 68 in the winter and 78 in the summer. Even though I am in the basement with my tanks the basement temp fluctuates with the seasons and the HVAC.. So I run a hotter tank 24/7 in the summer. This is because the MH actually heat the ambient room temp up as well. The thermostat is upstairs for the HVAC.

 

[beth]

Originally Posted by renogaw
if he sets his water to 80, won't that just give the lights a higher base temp to start with? meaning if its at 80, wont it run the temp up to 83?
No, because the the heater runs on a thermostat which will shut off at 80. If heaters didn't have thermostats, then they would just continue to heat up the tank until the the fish fried.

 

[zman1]

I believe renogaw has some validity to his post about the potential to raise the high end during photo period. There is a risk that it can and not just because you raised the heaters up to match will it automatically go the same on the high end, but you need to keep in mind it could go up
Example - 10 hour photo period
The two known temps. right now in this example
77 at 8:00AM
80 at 6:00 PM
I see this example below as a non issue when raising tank temp to 80 via heater to minimize temp swings.
77 at 8:00 AM
80 at 10:00 AM
80 at 6:00PM - (80 is the highest the lights can heat the water up and flatten out for 8 hours)
Where there is a potential to heat the tank higher than the old max of 80 with lights that can play a role in the example below.
77 at 8:00 AM
78 at 11:30 AM
79 at 3:30 PM
80 at 6:00 PM
We have never confirmed for sure this is the highest temp the lights can raise the water temp. We have only confirmed here is that at the VERY end of the photo period 80 was Max from a 77 start. What if you let the lights on another 3.5 hours would it stay at 80 or move to 81. This is how raising the heater temp to 80 doesn't mean for sure the max will stay at 80 when the lights are on during the period. If it takes 3.5 hour per degree raise what is the max since it didn't stay flat for anytime before the end of the Photo Period...
What if we started at 78
78 at 8:00 AM
79 at 11:30 AM
80 at 3:30 PM
81? at 6:00 PM
That's why I called it a balancing act.

 

[lion_crazz]

I am thinking if he keeps his tank steady at 80 degrees by adding an additional heater, the lights are then going to heat the water up to 83 degrees during the photo period.

 

[renogaw]

Originally Posted by Beth
No, because the the heater runs on a thermostat which will shut off at 80. If heaters didn't have thermostats, then they would just continue to heat up the tank until the the fish fried.

i'd assume his heater isnt the culprit though, but most likely the lights. if the heater is set at 80, what's to say the lights wont bring it up to 83?
yet again, we don't know what he has the temp set at...

 

[farnorth]

Wow... I did not check this post for a few days and I appreciate all the questions and suggestions. I actually have my thermometer set at 73, but it stays around 78.5 with the lights off (just the moon lights on) over night, then my lights come on from 2:30pm - 9:30 at the end of the day it reaches around 80.5 with my lid off my tank and around 81 with the lid on my tank.
Yes, I was afraid if I added a heater it would just raise the temp that much more when the lights came on.... but I don't know what to do.

 

[sepulatian]

How much water flow do you have, and is there space between your lights and tank? Is there ventilation? This post has been on my mind and it seems the true problem here is not raising the temp in the off hours, it is keeping your temp from raising when the lights are on.