Ammonia still keeps coming back, and loss of gill fluff (separate problems)

[MyLittleComet]

I've posted about the ammonia spiking before, but I really only got told what causes ammonia, which I already knew, and the different ammonias (harmful and non-harmful)

I had to almost completely drain the tank in order to move it to a new stand, and now 5 days later the ammonia is at .50ppm! (Ph is about 7.2, nitrite is 0, and nitrate is slightly above 0 i think, its not quite yellow, but not 5ppm either) There are NO dead animals or plants in the tank, there's no left over food or waste, I have no idea whats causing this. Is it the sand somehow? I've disturbed it every time I change the water so nothing should be caught in there or hiding underneath. I did an entire week of Seachem stability and added aqueon PURE balls after moving the tank. This tank has been established for over a year. I've only seen the ammonia spike after I put sand in.

And, Comet has lost his fluff again I dont have access to the ingredients for holtfreters solution, so I'm doing salt baths again since that brought it back last time. It disappeared nearly overnight it seems! He was fluffy one day, and the next, almost bald again.... I tubbed him when I was taking out water to move the tank and as soon as I put him back in I noticed his gills were almost bald and took him back out again for salt baths. (Pictures are 4 days apart)

Him and Meteor also keep refusing to eat anything... some days they'll eat, and then go several after without any food even though I keep offering it every day. I'm doing the very best I can but I feel so lost...

 

[wolfen]

if you have salt but haven't got the other ingredients for holtfreters you can still dose the tank to 2g per litre of water until you can get the other ingredients.
all dechlorinators take time to work so changing such a large amount of water can introduce a small amount of chlorine to the tank.
sometimes it's a good idea to use bottle bacteria to ensure the bacteria colony is kept the right size.
I don't put much faith in the bacteria balls as all they are are orbeez left in a solution of bacteria but because of how they absorb the water it would only be the surface that holds bacteria.
also make sure there is no balls left in the tank as they can become a hazard.

 

[MyLittleComet]

if you have salt but haven't got the other ingredients for holtfreters you can still dose the tank to 2g per litre of water until you can get the other ingredients.
all dechlorinators take time to work so changing such a large amount of water can introduce a small amount of chlorine to the tank.
sometimes it's a good idea to use bottle bacteria to ensure the bacteria colony is kept the right size.
I don't put much faith in the bacteria balls as all they are are orbeez left in a solution of bacteria but because of how they absorb the water it would only be the surface that holds bacteria.
also make sure there is no balls left in the tank as they can become a hazard.

Thank you, ill def make sure the orbeez are out of there. I had thought they were like popping Boba instead and would disappear :/ ill get some bottle bacteria and see how that works. I appreciate the response!