Yes, I have had issues; pumps burn out, fields needing extending, etc.
My tanks are huge -- 10,000 gallons. They are made by stacking the barrels in the photo.
I made a core sampler to keep track of the sludge build up in the tanks, which is what I am holding in the photo. I forget how long I needed to make it to reach the bottom of the tanks but for reference, I am 6' 6".