Originally Posted by ziggy222
the big drawback of sponge is this.sponge has antibiotics in it for its own health.if it dies, the antibiotics goes into the tank and it will kill all your corals in a large enough amount.thats why lots of people don't keep sponge and also thats why people don't put antibiotics in a reef to cure fish disease.
Can I ask where you heard that sponges contain antibiotics that will wipe out a reef tank? I found one reliable article about the antibiotic content of some of the sponges found in the Great Barrier Reef... http://www.abc.net.au/science/news/h...ish_195275.htm
but, nowhere did it say anything that would lead me to presume that sponges in an aquarium will wipe out corals or anything else if they die off. in order for your statement to be true there would have to be such a high concentration of antibiotics in the water to do harm... and anyone running a reef tank without a skimmer and proper filtration is asking for trouble anyways. A skimmer, good filtration media, and proper maintenance, will protect an aquarium from such an event as you suggest. Also, the use of carbon in a filter will help to avoid any issues. Antibiotics are "medicines" and carbon will soak these things from the water if they are introduced. Did you know that a tank (reef or otherwise) with carbon in the filter can be given a full strength dose of most any medicine and it will filter out of the water as soon as it hits the carbon. You could expect that tank to be completely free of any traces within 48 hrs... 24 if you have enough turn over rate.
Understanding that most people choose not to run carbon in a reef tank for fear that it soaks up too many needed nutrients from the water (also, this is not entirely accurate.. it's a matter of how often you are doing water changes to replenish the tank with the needed nutrients regularly), if there is die off of any sort in a tank, carbon can be a great friend.
I have had sponges growing in my reef tanks over the years... clear, white, yellow, purple, and even a bright orange red species have all thrived in my tanks at various times, and always in my reefs. The sponges go through various phases of die off as time goes on, changing forms and density according to what the environments allows. I have had some very sensitive corals in these tanks, and never was any harm done to anything from sponge. My worst battle with sponge was a white species that attempted to grow over some of my mushrooms. Once I removed the shade from above the mushroom, the sponge died back and then grew in a different direction into the shade.
Sponge can be very beneficial to a reef aquarium such as caferacermike has pointed out. Sponges are filter feeders, which means they help to clean the organic waste from the water. Some sponges are partially photosynthetic, although most of the common ones found growing naturally in a healthy reef tank tend to rely on shade and good circulation to thrive.
Not all sponges react the same way to air as was described, either, though it is a good idea to not expose them unless you know exactly what species it is and if it is safe or not. Some corals also have the same issues with air exposure.
As for tunicates, these are not even realted to the sponges. The only thing they really have in common is their sensitivity to their envrionment, and the fact that they are both filter feeding animals. Tunicates are members of the phylum Chordata, while sponges belong to the phylum Porifera.
So, would I suggest keeping sponges in a reef tank? Absolutely! My suggestion would be to keep doing your research, never take a sponge from a wild environment and introduce it to an aquarium (this could be deadly to your entire tank), and keep your tank healthy to encourage them to grow naturally. Choosing live rock from different places, different types, and using things like live sand and refugiums on your tank will all encourage new types of growth to develop over time. Have fun, enjoy, and just keep up with your maintenance... which is something you'd need to do anyways in order for the tank to thrive.