Planaria or???

I think thats exactly what they are. Thanks! After reading that article and some other posts on here, im curious as to the cause. Some listed were Poor filtration, Poor cleaning practices, Too high of a bio load, Poor bio filtration or simply poor bio filters, Too little flow, too much organic matter, deep substrate, low PH, and high CO2 or Low Oxygen. i dont suspect its any of these other than maybe the deep substrate. My tank is 45 gal and I use a Fluval 406 which is rated for 100 gal so im at the recommended double and then some filtration. I do a 50% water change every week, I scrub the sides and front, and vacuum any plant debris that I can see. My tank is dirted and planted so I cant really get the entire surface vacuum. All I have in the tank are 5 amano, 1 nerite, and i just yesterday got 6 otos. My tank has been cycled for awhile now so i dont think it would be the bio load. The flow seems pretty good to me. Lots of surface agitation. I suppose i could add a power head low in the tank to get some more flow in the bottom but I feel like that would make a mess with the dirt. There is a lot of organic matter because its a dirted planted tank. My substrate is pretty deep at 4.5 inches but I needed to raise the bottom up to get it closer to the light since i have a tall tank. my oh sits at 7.4 and 6.4 when i have co2 running. I dont think its high co2 or low o2 because the co2 runs for 6 hours a day and there is pretty good surface agitation to help gas off the tank. the entire surface ripples. Im gonna check all of my water parameters in a bit and then do a big water change tomorrow and see if i can get rid of them or at least thin their numbers.

+1 to everything said here, they're probably detritus worms and definitely not planaria. For future reference, planaria have triangular heads and don't swim, and they're usually seen oozing across the glass at night. The detritus worms can be a little gross to look at - one variety I had would leave its rear end above the substrate wriggling around and occurred in clumps - but I'd consider them a plus in a soil tank since they help break down waste. As a bonus your fish might try to hunt them, which will help keep the population in check and give your fish something exciting to do.

That being said, if you actually do get planaria don't ignore them. I had an infestation in my shrimp tank and the little monsters actually killed some shrimp. The white ones in particular are predatory and it seems they're not choosy about their prey.