So i screwed up i guess. i had a custom made 55 gal. tank stand built because the other was cheap and looked like it was starting to bow. The gravel in the tank was well over two years old and had all turned green from algae. The tank had a problem of constantly dropping ph down to 6.0. So i transfered fish to a barrel with their water from the tank. i completely emptied tank changed out stand put in new gravel(rinsed). i never rinsed out filters which is a penguin 350 and emperor 400. I filled tank back up with water from 75 gal. which is running a fluval fx5 on it and from 37 gal. running two penguin 200s on it. i used some water from the barrel so i only used about 10 gals of water from sink. i let it run for awhile and checked parameters 6.8 ph 0.0 ammo. 0 nitrite, 10 nitrate. temp was 83 degrees so i transferred the fish back into tank. it looked great no stress their swimming back and forth was admiring how good their color looked with black gravel and black background about four hours go by no problems so i shut off lights and the next morning was a rude awakening one discus was down on the bottom laying on his side with what looks like excess slime on him and spots of maybe ick looked like salt on his eye and couple of spots on his body. the two other ones had the excess slime the whole tank looked like it went into a cycle it is freakin cloudy maybe due to new gravel. So i checked water parameters its still all the same except ph is 7.0 i added aquarium salt and melafix pulled carbon left in clearmax and biomax and raised temp to 90 degrees this all happened yesterday morning all three are swimming around today still have excess slime and some white specs on their body. i just added more melafix for anti bacterial. is this all i can do or do i dose it again with salt did full dose yesterday. should i be patient and wait it out i just dont want to lose my discus two of them are like 6 inches big while the third is maybe 4.5 inches. please any info would be appreciated.