Daily variations and the reef system?

[ALW]

I have started a reef tank. It is a 20 gal long with a 15 gal refugium. As of now it has been set up about two weeks.

Currently it consists of:

3 inch LS bed, 10 lbs of LR, one gallon of mineral mud and about a softball sized clump of Cheatamorpha in the refugium and 24 gallons of SW (Total). 8 crabs, 5 snails and 6 shrimp I bought at the live bait store

A friend gave me the hard equipment (Tank, cabinet, base and canopy with the lights.) He said that they are full spectrum. There are two sets of two bulbs. One pair is all white and the other pair is one blue and one looks a light purple. He said that he had no problem at all growing soft corals with it. The canopy has a fan in it as well.

My water temperature ranges from 78º F in the morning to 82ºF at night. The ambient temp is 77-78º. If I use the fan then it ranges from 76º to 80º.

Please remember, when the tank is ready it will be mostly soft corals.

Is a 4º variation from morning until night a problem?

[cocoa_pleco]

might be a small problem for sensitive fish, but otherwise i dont think so

keep in mind NSW (natural salt water) conditions are 82f

[zackish]

If you are planning a reef aquarium or depending on what kind of fish species you planned on keeping you may want to consider getting some more Live rock.
Even if you don't like a lot of rock you should at least load up the fuge as much as you can.....20 lbs at least I would say.

[ALW]

I have an additional 10lbs of base rock in there as well.

[NickFish]

Aim for 1.5 pounds per gallon of live rock. Depends more on the rock of course, but 1.5 is a good ground rule.

I definitely think that a 4 degree temperature change is a huge problem. Maybe a degree or two now and then, but 4 degrees daily is huge! The hardy clownfish could do ok, but if you ever wanted to get something that is pass being super hardy, you'd need to stabilize it. If my reef ever dropped more than 0.5 of a degree at a time I'd freak out. SW is sensitive.

My 2cents

[ILuvMyGoldBarb]

Why are you getting that much of a temperature variation? If anything it should be the other way around, with your high temperature coming during the day. At what temperature do you keep the heater set?