Rising Temperature

[kspink]

Hi-
We recently got our 75gal running. We have an acryllic tank with a built in overflow and a wet/dry sump/filter. We positioned our heaters in the overflow and the sump. The tank has two large openings that have lids (one with a small feeding hole-also with lid). We filled with distilled water and the temperature was fine (75). We put in sand (about 2 inches) and added over 50 pounds of live rock and several pounds of live sand. At present we are building a hood to hold the light (standand fluorescent-not HO or VHO), but for now we just set it on top of the tank-with the lids over the openings water does not splash on the light fixture. We had this running with the light on the tank after we added the rock for a day (less than 12 hours) and the temp inside the tank went up to 80. It did not come down at night or the following day when we did not turn it on. We noticed that the acryllic was slightly warm but not hot to the touch. I have several questions.
Is the heating due to the light resting on the top of the tank? We are building a hood as soon as possible-probably this weekend.
Can the live rock survive without lighting for a period of time? It is cured. I am a little concerned about not lighting the tank because the pH is starting to drop-presumably due to lack of photosynthesis giving off CO2. If we have to choose between warmer water or lower pH until the hood is in place, which do we choose.
We left the light off today and opened the coverings in hopes of cooling off the water but I don't know how successful that is going to be.
Is it possible that the water in the overflow and sump, where the heaters are, are at different temperatures than the water in the tank? I find this hard to believe.
Help

 

[zafirablanca]

You will have to play with the settings on your heaters until they stabilize at a temperature that you want. For the most part, you can't just set them according to the guage on the heater, drop them in and forget about it. Adjust the heater settings, wait a day for it to stabalize and see what happens. By the way, I keep my tank at 80 degrees. It is not too hot. 75 degrees is too cold in my opinion. I kept my lights on the live rock because it came with so much coral, macroalgae, etc. Some people do and some people dont. Just be prepared to deal with some algae if you leave them on. For me it was well worth it.
Good Luck,
-Christine

 

[cboyfan2020]

what kind of pumps do you have in your sump? Pumps are known to raise water temp a couple of degrees. What is the temp around the house?

 

[kspink]

Not sure what the name of the pumps are. But, we had them running and the temp had stabilized at 75 for a few days before we added the rock and light. Not worried about the house temp because it is below 70 at the moment-summer will change that of course. Pretty sure it was the light heating the water. The temp came down some yesterday when we had the light off and the lids open, but it is slow-we have read that the acryllic tanks hold the heat better plus we had the windows open to let some light in the room. We have constucted a temporary stucture to lift the light off the acryllic until we get a hood built. Then we will just have to adjust the settings as needed to compensate for the heat generated by the light.
Thanks for the advice,
Katie