Roger - I didn't see any dead worms. In fact, most looked like they were THRIVING! Some looked more "waterlogged" than others, probably due to the damper conditions at the bottom of the grow bed.

The only reason why I say "parasites" in my original post is because frankly, I am not too sure what killed off all my fish. My last one to die definitely took a slow turn downhill, but when he died, I looked over his body and couldn't see anything obvious. His gills looked fine....I saw no lesions or raised scales......etc. In fact, he never even had clamped fins. Up until the day before he died, I would witness him try to eat, but he would spit the food out, and all my research points to something called FLUKES. But without a microscope, I can't prove anything definitively.

I also noticed him begin to rub up against things. So it either was a parasite, or it could have been the salt I added to the water (it was only 0.1% or so, to help with fish health). Otherwise, I have no explanation how this fish slowly went downhill when my ammonia, pH, kH, nitrites, and nitrates appeared to be safe levels.

So now, my system is relocated into a sunny part of my yard, and it's just filling/draining without any fish in there. It's been about 18 hours, and I already see a bunch of reddish, brownish sludge sitting on the bottom of the tank, which obviously dislodged and came out after I turned over all the hydroton media.

I will vacuum that crap out, and leave things running for another week or two before adding any fish in there. I just don't know if I should treat the water with those aforementioned items (PraziPro and ProForm C) as a precaution......or would I be wasting this expensive medication since I wouldn't be using it on fish (but rather an empty tank).