I'm very sorry for your losses and current predicament.
Everyone believes that the metal valves are polluting your tank. But the temp spike up to 90F would have killed most all of my corals, and they would have died over the next 2-3 days. You said that you were not sure if the valves are "metal=stainless steel?" or brass. Brass is copper and zinc, both really toxic to aquatic life. Try to find out from the part# on the valves what metal it is. If it's not brass, you are probably OK to just redo the plumbing and be done with it. You mentioned that the pH was low and started using a carbonate supplement, did you not regularly check you Alk before? Just asking.
Everyone believes that the metal valves are polluting your tank. But the temp spike up to 90F would have killed most all of my corals, and they would have died over the next 2-3 days. You said that you were not sure if the valves are "metal=stainless steel?" or brass. Brass is copper and zinc, both really toxic to aquatic life. Try to find out from the part# on the valves what metal it is. If it's not brass, you are probably OK to just redo the plumbing and be done with it. You mentioned that the pH was low and started using a carbonate supplement, did you not regularly check you Alk before? Just asking.