newbie with probs

Question
hi
i set up a salt water tank weeks ago some live rock , some lava , sand etc did all tests temp , salinity , nitrate , nitrite etc all good so put in two clowns and a damsel , all good still then had algi so shop owner said add crabs and snails , all going well . then thought time right to do a water change , so took out 1/4 , made up new right amount salt and temp etc before putting in . put in that night fish actively happy as norm , following am cloudy and no fish to be seen ...couple days later find them dead , snails seem dead too , what v i done wrong ?

Answer
Hey Louise

I think i know the culprit, the lava rock. lava rock is acidic and will buffer your PH down. Im thinking that you had a dangerously low PH before the water change, and when you added new water, the PH got buffered up suddenly, causing shock and killing your fish. i would take out the lava rock

sorry for the losses!