Time for the element that makes a ref tank a reef, CORALS!!!!!
Same as fish and pretty much everythuing else, there are many types of corals that you can buy. From these corals, there are three main groups that most of the corals land into; the Soft corals, Large Polyp Stony (LPS), and Slamm Polyp Stony (SPS)> There are also non-photosynthetis corals, but those are kind of hard to find, and really hard to keep. As is with most things, these three groupings of corals come with thrir specific care requirements.
When you are starting, a good coral to start with ais from the soft coral group. This is ebcause most of them grow fast ebough to satisfy a beginner reefer, and they are east to keep. Most o them can tolerate a little bit of neglect, and less than perfect water chemistry. In fact, things like Xenias, Green Star Polyps, Yellow Polyps, Some kinds of mushrooms, and some Zoanthids and Palythoa are so easy to keep, theat many people have had what was once a small segment of one turn into an invasive weed that covers every nook and cranny that ther is in the tank. They are also good for beginners because they have few calcium and alkalinity needs, so youdon't have to test and dose for them.
Most soft corans are very peaceful, as they dont send out sweeper tentacles which can sting other corals. They also generally don't need that much food to eat, because most thrive off of sunlight.
Almost all soft corals don't need all that much light, even though they are photosynthetic corals. Almost all of them are very hardy, and they can regulate the amount of algae in them that can produce food.
As for flow. Most fost corals don't really need a ton of flow. In fact, most soft corals NEED very little flow, like muchrooms. A good rule of thumb for soft corals is you need to provide enough flow that can keep the polyps clean.
As is with every coral, soft corals need to grow. Many, like toadstool leathers, can grow very big very fast, so when placing your corals, you have to think into the future, and plan accordingly.
As said before, most invasive corals are soft corals. Almost all of these soft corals can't grow on sand, so if you really want the epic color and movement (Espetially Xenias) in your tank, but don't want them smothering everything, place them in anisland on the sandbed.
even though soft corals are some of the best beginner corals, they do have their drawbacks. The larger ones often lack the coloration and vobrancy as most other stony corals (Most ones that get to be masive are a kind of drap brown color). Also, most soft corals are toxic. Something like zoanthids have a deadly toxin in them called palytoxin. If you cut one and you see a whitish lime coming out of them, get your hands out of the tank ASAP. Otherwise, it will penetrate your skin, and could kill you. If it gets into the water, just do a few, 50% water changes every day for the next week or so, and your tank should be fine. However, many people get scared of zoanthids and palythoa, which is a shame, as they are some of the brightest colored corals that you can buy, and most are cheap. The amount of palytoxin that they excrete from theit bodies isn;t even that much, and if you catch poisoning early, it isn't all that hard or super super expensive for you to be saved.
Here is a quick list of some of the good beginner soft corals and where to place them in the tank.
As the name kind of siggests, these corals have large, stony polyps. What this really means is that the polyp are on a stony skeleton, and they need dosing of certain trace element like clacium in order for them to grow.
Most LPS corals send out sweeper tentacles, which can badly sting and kill corals that come into contact with them. Therefore, you have to plan your placing accordingly, while also giving them room to grow.
Unlike most soft corals, most lps corals do need food. People often feed frozen food like misis shrimp or LPS pelets. They should be fed at least once a week for optimal growth.
Here are some common LPS corals that are good for beginners
SPS corals are what most people usually think of when they say corals. They are the most common reef building corals, and what most hobbiests dream to have dominating their tank.
Many people think that SPS corals are hard to maintain. That is really true for Acropora sp and some Montipora sp. Most other SPS can tolerate a bit of neglect, and are really a small step up from LPS
Sps are some of the fastest growing stony corals, so they need a lot of calcium and alkalinity dosing, and many people that have a SPs domianted reef have to use several methods of dosing.
Sps corals generally like medium to high light and flow, espetially the Acropora, as they are primarily photosynthetic.They also need high flow because they need the middle foo the colony to sbe not stagnant, which can cause the coral to die.
The polyps on SPS are small, so it is kind of tricky to feed them, so most people dose a micro food like oyster eggs and brodcast feed the whole tank.
Here are some more beginner friendly SPS corals