ok, i'm quoting the moderator, thomas, from another thread:
"Why change from CC to SSB or DSB?
Most of us will not use crushed coral because it is a large substrate that traps the fish waste and uneaten food that has to be vacuumed before it creates nitrates, which it will anyway. Crushed coral does not provide a very good biological zone, and many tanks are setup with CC from the get go through lack of knowledge or because it is the only substrate that an LFS sells and tells you that it is all you need, using a selling point of CC has buffering power. I have personally battled nitrates over 100 ppm during my days of CC and UGF doing frequent large water changes. So many of us have been there and had high nitrates, did a water change to lower them and they were back in a couple of days. CC has sharp edges, which is undesirable for inverts, like anemones walking around, pods or worms. No getting around it CC is high maintenance and can lead to poor water quality, frequent maintenance, sick livestock, algae blooms and more.
"Sand on the other hand has more benefits. These include having far more surface area thereby making it able to handle a higher bio load of bacteria. It is less dangerous to your infauna and has a more natural look in the tank. If going with a DSB Deep Sand Bed you can have other benefits as well like finishing the denitrification or providing sand sifting, burrowing, or tunneling fish and critters a place to play. The denitrification process predominantly occurs in deeper substrates and in areas of stagnant flow where oxygen levels are depressed. And this is why deep sand beds are effective as a nitrogen export mechanism. As water slowly diffuses deeper, aerobic organisms strip all available oxygen for respiration. In the deep, oxygen-deprived layers, denitrifying anaerobes are given the opportunity to convert nitrogen compounds into nitrogenous gases, which escape via tiny bubble out of the aquarium. I believe this process can also work on a limited basis in shallow sand beds. My sand bed is no more than 2 inches deep in some spots."
Having said that, there's nothing more we can do to try and get you to switch now. You should do it now, as it will be so much easier.
Now, that's not the reason you posted this thread, so i will linger on that subject no more.
(don't worry, i think most of us started with CC!!! Darned LFS!!!!!!)
As for your question: The zoos and feather duster have about a 1% chance of surviving a cycle, so IMO, take them back to the LFS, and ask if they can hold it for you or exchange it for store credit... blame it on them, and explain to them that the guy knew you were just purchasing the tank (he sold it to you), and that he should've known that you can't put corals and inverts into a cycling tank. Good luck!!!