possible contaminate in our salt water fish tank

Question
I have a 55 gal. salt water fish tank. Sump filtration. bio ball container.  not sure amount of live rock. quite a bit with fake coral. hippo tang, spotted puffer, flame angel, fire fish, clown, sail fin tang, and a few other fish with shrimp and crab.  I went to vacuum out the debris and such from rocks using tubing connected to a drill pump. one end of tube was in tank, the other in sump tank allowing water to go back in to be filtered.  I changed filter after.  a few minutes or so when finished I noticed a haze in the tank and the fish appeared stressed breathing heavy. and slow.  pH was very low, added buffer. salt was very high added prime with water. did water change.  did 10 gal. at once instead of usual 5 . noticed hippo tang had white blotchy on stomach. added prima fix and mele fix did another smaller water change, slower this time. fish store said first one was too fast and stressed out fish. I cleaned all filters and charcoal bags.  Not sure if and oil was possibly inside tube/drill pump or soap got in water. we have a special nozzle for soap. soap might have been left and it was slightly open.  Fish still aren't right. Too difficult to get them out.  what can we do or add to help? please help Thanks

Answer
firstly you should remove the carbon if your treating your fish, this will take any treatment out of the water and render it useless.

i would keep up small waterchanges every other day and add extra carbon, try and feed the fish little and often to help boost their immune system. i wouldn't treat the fish again for a good week, just hope that an increase in carbon will remove the contamination. also try poly filters, they change colour to give an indication as to whats in there.

try and keep the PH, temp and SG as stable as possible throughout the waterchanges, saves the fish getting too stressed.

please let me know how you get on.