Water temp?

I have read a lot about the the importance of maintaining the appropriate temperature in a reef tank, but am still unsure about a couple of things.

We are currently cycling our tank & leave the MH on for about 5 hours a day. When the lights go off, the water temp runs about 80.2 degrees. Just before the lights come on, the temp is about 77.5.

I'm thinking that once we put livestock in the tank & have to keep the MH on for a longer period, the temp of the water will go higher than it's been running so far.

My question is: How much of a fluctuation in a 24 hour period is too much?

If it makes any difference, I plan to have the following in my tank:
mushroom polyps
button polyps
frogspawn
pulse corals
cleaner shrimp
pair of common clownfish
1 hippo
3 blue-green chromis
1 coral beauty
pair of royal grammas

Thanks for your suggestions!
julie

 

My tank usually goes down to 78 by the middle of the night and it goes up to 80 during the day. I think your ok. Do you have a heater running on your tank?

 

I would say that is right on the borderline of being ok. I don't like my tank to go above a 2 degree fluctuation. As long as the fluctuation is gradual I think it is ok.

 

Your fluctuation is not that bad, fish and corals can tolerate a fairly wide range of temperatures, 72-82 about. As long as it is a slow rise/fall you'll be fine. Now if your temp. shift gets a little out of control, I would say about 5+ degrees in a day on the safe side, then it means your lights are adding to much heat. You can then get a cooling fan if you don't already have one or raise them off the water a bit.

 

Thanks for your input.

JohnnyBoy - No, we do not have a heater.

GuitarMan89 - Our lights are 8" - 9" above the water surface & we have a fan in the top of the canopy to help draw the heat out. We leave the fan on even when the MH are not on.

julie

 

For your piece of mind, if you can hook up a small fan (possibly a computer type etc.) and have it on the timer with the lights.

 

Why run the M/H to cycle a tank with ?

 

reef tank tempreture should not fluctuate more than 2 dgree per day & if you want to have fan that good put dont direct the fan on the water the chance of evaboration will be more you will have to top up too much water daily & the salt constration will increas mean more fluctuation temp & salnity wich is bad. by the way if the temp drop very fast in any tank chance of ich paracide to be there . keep youre tank staible as much as you can try to have cheller better

 

I have to agree with tangster, there is no need to run your light during cycle, all though that will give you an idea on how hot the tank will get when you finish cycling and add the live stock to it, but for the time you are cycling the light are going to create a problem with the algae bloom

 

If (as most are) cycling with live rock, light is not only beneficial but essential. There are "good" organisms that benefit from the light let alone all the creatures that may be dormant in the rock. Algae is a sign of a healthy tank and it must run it's course. Many an aquarist has done the "no light" thing and when they added the fish etc. after cycling and ran the lights, boom! tons of algae, now more than ever because of the addition of inverts etc. Run the lights.