Live Rock (or where did THAT come from)
Live rock (LR) is the main filtration system for your cube. It is the remains or pieces of coral reef that contain the beneficial bacteria for your tank. It also provides shelter, attachment for corals and contains coralline algae and small critters. You can read tons on LR, which I'll leave for you to do. Live rock is added to your cube when ready for startup and your SW is mixed and ready. After cycling, you may see corals arise, critters (copepods, amphipods) and also pests (later talk).
Cured vs. Uncured
Sounds like a ham, right? Uncured rock is LR that comes right out of the water and has sat for awhile. Some of the organisms die off and when put in a tank, a large ammonia spike can occur. Cured rock is that which comes from your lfs and has already gone thru this dieoff process. Cured LR can have miinimal dieoff if it is rapidly shipped or shipped in waterf. Uncured rock should never be put in a cycled tank with livestock/corals. The ammonia spike will kill them. Truly cured rock could. So, which should you buy? Your call. Uncured rock may take longer to cycle, have an odor, require more work and have more die off, but, it also may arrive with more coralline algae, beneficial life (and pests). Cured rock cycles quicker, but, may lose some of the good stuff. If you are like me, with an empty new tank, you may want to go with uncured, which is what I ordered.
What do I do when it arrives?
Depends on what you are getting. Talk to the dealer before buying it. Many recommend scrubbing the rock with a toothbrush. My dealer did not recommend it. I think it's safe to say that rinsing it in SW and picking off grossly dead material and sponges (if they are there) are wise.
How do I cure my LR?
Easy...you do it in your tank when you're ready to go. Never add uncured rock to an already established tank. If you chose to do it separately, you will need:
2) a large bucket or one of those Tupperware like storage containers that you can buy at WalMart or Target
Here is one of many links to give you a guide:
1) Your lfs: The easiest source is your lfs. Check out prices; look for good color; ask how long they've had it for. I was unhappy at 4 of my local shops.
2) Internet: I did a lot of research on this. Four of the most popular internet sources for LR were:
I decided to go with (a). You'll see how my choice worked out when it arrives
3) Make your own: some people do this and although I never reseached it, apparently it is made with concrete and particles that later dissolve to make porosity. One website that has a DIY manual is http://www.thelebos.com. This might be an option for those people who are on a strict budget.
In general, the estimate is 1.5 lbs of LR per gallon of water in your tank. This is just an estimate. For my 24, I ordered 20lbs since the rock is light. If the rock is dense, you may need more. If it is very pourous, you may need less. Ask the dealer.
Types of LR
Just a few examples of the most popular types:
1) Marshall Islands
4) Tonga branch rock
5) Atlantic base rock..generally a very dense rock and used to as a base rock to save on the cost or add support to the live rock.
6) Aquacultured LR.....farmed LR.....see Tampa Bay link above. They actually 'grow' live rock off of Florida.
Live Sand and Substrate
There are many types of substrate to use in your tank. Unlike a FW tank but similar to a cichlid tank, the pH of a SW tank needs to be higher, around 8.2. Calcium carbonate, the component of seashells, provides that buffering capacity. The average recommendation is 1 lb of substrate/ gallon of water. Depth should be 1- 4 inches deep. Some types of fish need a deep bed (eg, jawfish). However, the deeper it is there may be dead areas which can have a negative effect on the tank. Choices for substrate include:
1)Live Sand: this is sand that contains beneficial bacteria. There is some controversy here. Many say that your sand will seed anyway. Others say that it will 'jump start' your tank. The best live sand is that which you can get from someone elses tanks that contains live organims such as copepods, etc. Some people sell this on Ebay. The other source is store bought.
2) AragAlive: this is a store bought aragonite sand that has beneficial bacteria. It comes in a 20lb bag. Many feel it is the best substrate in the 2-5mm size. Perfect blend of buffering capacity (that crushed coral lacks), porous biolgical capacity, and compatibility with sand loving organisms.
3) Florida crushed coral: Crushed coral has been pretty much avoided in recent years, being a poor biological medium and not very friendly to sand loving organisms.
4) Other types including Fiji pink sand, black sand, Tahitian Moon,etc
5) No substrate: some people go 'barebottom'. Not my cup of tea.
DSB or Deep Sand Bed
A deep sand bed is one that is built up to a layer of 4 inches. This creates dead areas where anaerobic breakdown of nitrates occurs releasing nitrogen gas. It works very well in keeping nitrates reduced, however, most feel that in a nano system, the area is so small that it is not worth it. If not done well, the DSB couild also work as a trap. This is an area for you to read up on to make y our own decision on
A plenum works on the the same principal as a deep sand base,however,people create this using electrical eggcrate and PVC tubing. It creates a dead layer of undisturbed sand and water where anaerobic metabolism breaks down nitrates into nitrogen gas which bubbles up and out of the tank.