As well mine is second hand, and is a test drive to see what I want in one. I have noticed in the last couple of weeks its running more and more and not putting out as much heat, so I am thinking I may need a new one this summer.......though it just may need a good cleaning......or I am imagining it.......
Some theories and philosophies I have.
What temp? Good question, play with it a little.....since SPS is the most sensitive and thats what you and I keep, we will discuss with reference to that. Current data I have seen......puts the average reef in the 82-84 degree range. However, it has been found that 86 is near the upper limit for SPS and RTN occurs near there. I have heard that better colors and growth occur at slightly higher temps. For a long time I kept mine at 78 which is towards the lower side, when I didn't have a chiller and didn't want to push it. After hearing about the above information, I upped it to 80 and have not had any ill effects, in addition cuts down on the need for the chiller to work extra. Currently mine fluctuates between 80-81.5 degrees.
If you want to keep the tank on the cooler side and very tight in temperature without much deviation. By a chiller that is oversized for system that is inline, not drop in, that has more cooling capacity that heat generated and just "kills it" so it doesn't have to run all day to keep up.
Why do you want it stable as possible and not fluctuate all day?
My theory: Because SPS are so sensitive to just living and small changes in Alk/temp/salinity can kill them, I would only imagine the window to get optimum growth rates is down right invisible. Sure, with levels in the "acceptable" levels one can get stuff to surrvive and grow, but if your interested in getting those 1/2" frags growing out of the tank as fast a possible the params need to be solid as a rock. I imagine that say the growth rate is a reaction that only takes place when x,y & z are within a certain level growth starts. However, if they are at a certain, optimal level growth rate is maximized. Any deviation and the process is either slower or worse stopped. Think about this happening all day and say your temp is fluctuating between 80 and 82 every hour, at 80F you get 50% growth rate, at 81F 100%, 82 back down to 50%. Its a constant starting and stopping much like if one were hitting all redlights instead of green on the street. Which gets you to the finish line faster?
Now take this into consideration with all parameters in your tank....the smoother and flatter your params are...the more happier, healthier your corals are.....hence more growth.
I realized this when I observed just how much my growth rate went up when I was continously dosing two part throughout the day rather than the yo-yo cycle of daily dosing.
I am trying to incorporate small choices like this that may decide the difference in 1/2" month growth or 1/8"...............
With a chiller its hard to keep your temp spot on and may fight with the heater if big enough and depending where each probe is. Hooking them both up to a controller with its own quality probe is key in closing that gap. A two to three rise and fall a day I believe is the most is recommended. Many cycles of this could happer them. I will touch on why below.
