In order to get those levels of ammonia, the biological filtration in the first place must have suffered a major setback for one or another reason.
I am not aware of the timeline of events, when and what was done. You know better. But the increased flow rate will help in the long term, preventing any setbacks like this. A turn over of one time the water volume an hour is extremely insufficient, whichever way you want to look at it.
A 75% water change will remove 75% of the 5ppm ammonia, providing one has read the test well. So when you do a 75% water change, test just after the water change, you should have a readable ammonia of 1.25ppm roughly. 50% will only reduce it to 2.5ppm. This will give you an idea if the test is accurate. Prime does skew the test reading depending on the water chemistry.
It is pretty normal to get a very high ammonia level in an uncycled tank full of fish.....But the ammonia should really be going down to zero in a week, especially in a previously cycled tank, unless there is something dead and big rotting in the tank....
Ok, no big monsters dead in there YET. LOL
I think my plan of action is simply going to not feed them for a few days, while still doing WC.
IF it is continuing to decrease in numbers.
ONce the numbers go back to zero I will offer food ONCE daily and see what happens especially with the new pump doing 5X as tank volume. THen we'll see what happens.
With this increase in the volume and flow going through the barrel filter I see a lot of crap flying around AND also of course going into the fish tank.
I have put nylon screen material over the sump pump and the sponge type filter back over the sock pump and I also put a sponge filter over the circulation pump that sits on bottom.
SO, my thoughts are basically something happened to the bio filter AND it also had not enough flow rate. I mean with the water temp's sometimes going from 50 to 60 in one day if I'm not careful on the timer or even down to 48 that is not good for the BB.
So after a few days, four? Who knows. I am HOPING all the crud and stuff floating around will be be settling by then or getting used to the new flow and that the sock filers and sponge filters will continue collecting a lot of that. So in a week should be back to at least cleaner looking water.
I bet some of that stuff floating around IS BB though, so I guess I wait til it re-establishes itself.
Just 2 weeks ago I was feeding 3 big meals per day and it might spike to .25 then go back down within a few hours and then zilch in the morning. Same fish.
My FEELINGS are that the water temp's got down too cold for too long. Like 46 degrees for more than 24 hours.
When I noticed this, it took half day to get it back to just 55.
So theres my plan, I'll let everybody know what transpires.