Extreme Muck In Water - But No Fish
Curious on this one. I'm setting up a new 36g freshwater tank. I'm currently doing a fishless cycle, all going good, been about 3 weeks. Tank has gravel, fake plants (sigh, I know lol), one smallish piece of new Driftwood, Fluval FX4 filter set up as Fluval sent it, lid on, heater, Bubbler. Everything that went in to tank and filter was washed ahead of time. Added bacteria in a bottle, dosing with ammonia, no fish food. No water changes. Water has been pretty clear the whole time, on and off bacterial bloom, some tannins. Currently ammonia going from 2ppm to 0 in 24 hours, nitrites spiked, and nitrates about 40ppm.
I opened the filter and added filter floss, changed bio media to Matrix (yay!), added Purigen, and removed Fluval BioMax bio media and hung in a media bag in tank. I'm not concerned about delaying or even starting the cycle new again. No fish, no rush. I just wanted the Matrix. I rinsed the Matrix off very well ahead of time.
But my question is... When I turned the filter back on, man was the water mucky! Couldn't see more than an inch or so into the water. Mostly cleared up in 24 hours, and in 48 hours pretty darn clear water. So all good. But curious on what that muck was? I've seen it in years past after filter maintenence, but that was when I had fish stocked. No fish this time. What was the muck? Only thing I could think of was either muck from the driftwood, gunk from the old filter bio media (what gunk?), dust from Matrix (but it didn't look like dust), or it was a TON of bacteria. "Cloudy" is the wrong term, it was like a stirred up river bed.
Again, all good, everything's fine, just curious what the gunk was since it wasn't fish waste.