tl;dr: why do I have this brown floaty stuff and debris all over my 40g 

I’ve had two tanks going forever. Like 8 years or so? They were both looking pretty rough at the end of the year, so I spent some time at the beginning of this year cleaning them up. They both had some crazy algae and different plant overgrowth. 

In June, I invested in a fluval 307 for each of them to take the place of the HOBs and sponge filters that were there  

The filters are definitely working. Lots of stuff to clean when I’ve taken them apart. 

Since I put them back together, I still have problems with this 40g tank. I posted a while back but didn’t get any responses so I thought I’d try again.

They have the same heater, the same light, the same filter. They each have an air stone. A net bag over the filter intake that i clean regularly. I realize the 40 gallon breeder is a lot less deep so the light affects differently, but I have more plants in there that need brighter light and I let the floating plants take over more.

But no matter how much I spot clean it, the 40 gallon always has some like floating crap that looks like dead plant bits or something that’s always getting stuck in the roots of the floaters and just everywhere. I have a little vacuum cleaner. I just used like maybe five nights ago and this is what it looks like. This is after I cleaned out some of the bigger pieces of muck .. brown gobby stuff … that were stuck in some of the plants.  

I took pictures of the 55 gallon just so you can compare to see what I mean. The floating roots are pristine in comparison and the whole tank is just much cleaner.  

40g has pea puffers, Corys, a few oto somewhere, and 10+ amano shrimp. I put snails in, but they obviously get eaten immediately.

55g has rasboras, 2 kinds of loaches, bumblebee gobies, a betta, shrimp, a few amanos, and snails — ramshorn, bladder, and MTS. 

Help needed on my 40 gallon breeder