Hi
amanda. A refugium (with a deep sand bed--DSB) is going to do several things for you. First, because you have the DSB your nitrAtes (the final product in the ammonia oxidation or nitrification cycle) will be converted in the anoxic regions by anaerobic bacteria into nitrogen gas (this is what comprises approximately 80% of the atmosphere). Also, because you'll have this sand bed, you will be able to culture a variety of very small to microorganisms--known as "the pods"--isopods, arthropods, copepods, as well as numerous tiny worms and such that will not only consume a fair amount of detritus, but will feed certain fishes and many filter feeders.
I will strongly suggest you break up your heating, first NO Ebo Jaeger, I've been hearing far too many horror stories to not directly dissuade you from purchasing this product (they're often getting stuck in the "ON" position), and to divide the heating into two heaters. For your 70 gallon system, you would do well with a sump/refugium on the order of about 30-40 gallons (if anyone disagrees please voice your opinion!), which would give you a total volume of around 100-110 gallons. Using the 2-3W/gal rule, you would then use two 200W-300W heaters--place one low down in the tank, and the other low down in the sump/refugium. Believe me, by dividing heating duties you'll again spare yourself some heartache.
(You'll need a good pump for the sump/refugium, use the money you were going to spend on the Magnum for this.)
danm is spot on about the live rock, don't EVER take anyone's word for it that it's cured, unless you SEE it setting in a dealer's tanks and there is no smell coming from it. He
could have linked you directly to our library, so I'll do it for him (you silly man)
http://www.reefs.org/library as well as kick you to another excellent site (I am also associated with this site)
http://www.wetwebmedia.com This site also has a forum,
http://www.wetwebfotos.com/talk What you'll want to look for are the newbie and set-up articles, as well as the copious FAQ's. When stocking with live rock, the basic rule of thumb is 1-2lbs/gallon, so 90lbs would give you just a bit above the bare minimum. I'll suggest that if you
think you'll want more, get it now and cure it all together.
GET A QUARANTINE TANK!!! This is, without a doubt, the BIGGEST mistake I see people make, over and over and over again. They get their stock (fish AND inverts) and throw it into the display and it is
so easy to end up with problems that you'll be hard-pressed to sort your way out of without one. Quarantine everything, this is more than a suggestion here. Protocol for quarantine is 30 days
minimum. Quarantine doesn't have to be a proper fish tank, it can be just about any watertight container that has a decent surface area to water volume ratio (this is why tall and narrow is no good). Lots of folks just use Rubbermaid tubs/containers for this end. Keep it bare-bottomed, and use some pieces of PVC for the animals to hide in. Once your live rock is cured you can also keep a piece or two in the quarantine system for the animals' psychological health.
Oh my..what else? Well, just visit the links I've provided you, I wouldn't be surprised if you find subjects none of us thought to cover. Good luck!
