BSI gel is generally safe to be used in marine.i have been using it since day 1 till now.no adverse effect to corals as long as u don accidentally glue it to their flesh.
Pm me for photos if u are interested. U can refer to this website for details.
http://www.madpetz.com.sg//index.php?main_page=product_info&cPath=1_127_164&products_id=587&zenid=db7otkre7bmu2bsk7oi7p2o263
contact me at 98734469
Hc-100a -selling at $130
Sms at 98734469.
will show u the demonstration before purchase as this chiller is for standby usage at the present moment in case the other working chillers fails me