Here are two good articles concerning >>toxins
<< and >>sponges
<< you may find interesting.
For the most part though sponges are not recommended for a beginning aquariust nor a new tank set up. They are very dependant of stability and very prone to algae issues. For the most part they do not need light except for blue sponges and are strict filter feeder and need good waterflow.
You must be extremely careful never to expose them to air or "airbubbles". If they get into the tissues of the sponge it clogs the pores and prevents those areas from being fed properly and that section quickly dies. The resulting dead tissue starts a chain reaction and the sponge is rarely able to be saved.
Feeding should consist of fine filter foods and if available live phytoplankton.