I have a 220 gallom SW aquarium with fish and live rock and a couple of soft corals. My problem initially was a lot of aptasia which I controlled with aptasia X to some degree. I decided to put some peppermint shrimp in the refugium sump and let them eat the aptasia and maybe place a rock at a time in there so they could clean one at a time. What happened is they migrated through bioball coulumn into pump intake chamber and perished in the pump. I thought I would try and place a screen in the chamber to prevent them from getting sucked into pump. This seems to have been a bad idea since the screen I used is possibly aluminum or zinc coated. I noticed the aptasia's dosappearing at an alarming rate, which normally I wouldn't mind, but along with them of course went other creatures, ampipods etc. Fish appear to be doing fine and are eating as is anenome, feather dusters, leather coral. One coral is not looking as good as usual. I of couse removed screen and did a 20% water change so far. I have read about products such as NovAqua which can reduce heavy metals. Any suggestions on how to best recover from this problem and restore tank back to health? I don't believe copper is used in screen.