I just added panda corys to my 40G breeder yesterday and their rooting kicked up a huge amount of the very fine decayed spiderwood that sits atop the sand, making the water pretty murky. I actually just did a water change with gravel vacuum on Monday so it's not as if I've been letting organic matter accumulate. However, my tank is planted and I have some large pieces of spiderwood that make it difficult to vacuum everywhere. I am currently running an AC 70 (as well as a water pump to add circulation). I squeezed out the filter media in tank water and ran a DIY gravel vacuum (without doing a water change) for a long time yesterday and removed a ton of the mulm and that helped a lot, but it's not entirely gone. I've heard that corys like the substrate to be very clean so I'm really hoping there's a way for me to modify the filtration and/or current in my tank to pick up more of this stuff. Furthermore, I tend to get a good amount of snail and shrimp waste accumulating. I do have a Tetra Whisper EX30 and an EX70 that I recently picked up on clearance for a VERY good price. Would adding one of those on the opposite side of the tank help suck up the particulates the corys kick up before they can resettle on the bottom? (I would swap out the media for something without carbon by the way) Thanks!