Ammonia Spike -- Why??

Sounds like to me it is a over feeding issue in conjunction with increased waste production by the remaining inhabitants.

The steps you have taken to clean your new/used filter should have been more than adequate to remove any residual bleach IMO.

Yeah I am leaning towards overfeeding + more fish waste + filter change

Sooooooo 30% water changes daily, anything else I should do? So far **knock on wood** the clowns don't even seem to care. They are acting normal, and continue to beg for food...
 
The first night I changed out the water 75%. It took 3 days afterward for the ammonia to go (I did 60% water changes daily), about 2 days of 50% water changes for nitrites to settle to 0. Boy I sure did a happy dance when it settled! Lots of plants and prime helped, too.
 
Yeah I am leaning towards overfeeding + more fish waste + filter change

Precisely my thoughts.

The bio-media you moved over from the Emperors is great seed material, but it's still a new non-established, non-cycled filter. I use the same method of using the ceramic media from my old filters to seed my new ones, and I have often seen a small mini cycle lasting a week or two, even without feeding extra food. With the added feeding coming so quickly after changing the filter, while the filter is still getting established, my guess is that it just couldn't quite keep up.

I highly doubt there's any chance that any bleach survived the process you used to remove it. That sounded pretty hardcore to me.
 
Just a follow up, yesterdays readings:

Ammonia: 0
Nitrite: 0
Nitrate: 10ppm

Did a water change to remove the Nitrates, all seems to be well now. Tank is still cloudy (bacterial bloom at this point) -- but water is good now. I did large water changes (thanks Lise) -- last one being 50%. I also squeezed the sponges from my other tanks into a bowl, and dumped that into the 125g daily (I think that helped a lot) and I did not feed at all during the Ammonia spike.
 
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