A few suggestions,
Tank bio filter is not caught up.
stop adding things, feed light, dont add anything for 1-2 months. confirm ammonia test with another kit. get a bottle of seachem prime, if things look odd, add its dosage (one cap per 50 gal so it will last you a while). It will bind the ammonia etc so it is not harmful. Great insurance to have around.
after this, 1 month between additions. dont over feed as this increases load on bio filter.
Im not sure you are mixing your salt correctly, what size pump are you using in the 5gal bucket? Salt should not sit on the bottom dissolving.
Mix new salt using this method.
rodi in bucket, heat and aerate by running large pump BEFORE adding salt. Salt dissolves better in warm water than cold water
once to temp, slowly add salt (it should dissolve before hitting bottom) until you are up to SG
After its up to SG let the pump run for 24 hrs (or more is fine)
before water change check temp (alk, calc, ph etc isnt bad to check also. You can get alk to precipitate out if salt is moist before using or is added too concentrated) I recently tried to use some salt I had forgot about (Stored improperly in the bad too long), after mixing and testing alk it was like 5 so had to dump it. I could just correct its alk but who know what else went wrong with it.
I would do less water changes for now. move to monthly right now, only 5 gal.
how tight is the glass top? remove glass top until you can be sure you have proper oxygenation/temp control. You can get netting etc to stop fish from jumping.
http://www.bulkreefsupply.com/diy-aquarium-screen-top-kits-1-8-netting.html
Do you have proper aeration?
http://www.reefkeeping.com/issues/2004-09/rhf/#d what is your low ph (just before lights turn on or early morning before room is lit by outside) and alk level?
There are some battery operated temperature gauges that have a high/low history on them and alert. this might be helpful.
I try to buy an ammonia alert tag whenever i cycle a new tank. It stays in the tank all the time and changes colors to indicate ammonia.
It lasts months and lets you quickly check ammonia levels whenever you like.