Quaranteen Tank Need Advice

[svirid]

Good day,

month ago I have decided to get a new fish, so I have setup a QT, it has 400MaxiJet
, hang on filter, heater. I had no chance to get a fish till now, so tank was running all that time.
I filled it partially with the water from the tnak and apx 80% fresh salt water.

I checked water parameters today everythig was awful, nitrite, nitrate ammonia really high.
I completely emptied now and filled with the 100% fresh salw water, and started to run again.

Can u please tell me why the water got that bad. I had food in there, maybe its because I took water
from my main tank? I have Stabilization System and AMMONIA guard by Seachem but I did not use
it, because the tank was empty. Should I use it all the time, nometter if fish is there or not?

Thank you for your help.

 

[nanoreef11]

In the filter is there a new pad? If so the tank has no biological filtration at all and it is trying to cycle. Put a pad from your main tank into the quarantine tank and let it run for a week or so hopefully you just have some nitrates by then and you can just do a partial water change.