how cold is to cold

depends a whole lot on the SPS you're keeping, but 73 is too low. Why is that? What wattage is your heater compared to the size of your syste,?
 
I've run my SPS tanks on the low side 77/78 for years, however, I don't think too many people are going to recommending anything south of 75 unless you're talking about a cold water reef.
 
I have been running my tank 73-75 with SPS and everything. Everything is fine and growing!

-Dave
 
You can run it that low but growth, color, and overall health won't be what it should. Shoot for somewhere in the range of 78-85.
 
What was it during the day?With SPS your coral can STN,or RTN with huge temp swings.IME 73 means trouble for SPS.79-80 is my reef.
 
my tank stays at 75 most of the day, but with it getting colder outside its been dropping, i went out and picked up a new bigger heat and got it up to 78, i hope that big of a change in temp from 73 to 78 does'nt kill everthing.
 
it took it about 3 hours to rase it up to 79, everything looks ok only time will tell, thanks everone for your help.
 
Back
Top