Just an account of an experience we had a while back...
We had twin 1000 Litre tanks incorporated into the hull of a 10 metre twin diesel offshore RIB a good few years back.
We had one major problem mixing fibre glass and fuel !
Large tanks such as this obviously required internal baffles to prevent a half tonne of diesel sloshing around ( not great for directional stability!)
The only problem was that the baffles were also glassed into the inside of the tank. With heavy use a baffle sheared slightly away from its mount and the two broken ends began cheese grating very fine fibres into the fuel which invisibly clogged the Racor filter for that tank and engine.
All we knew was that the affected engine would run fine for an hour before chugging to a halt when the fuel filter was clogged invisibly as the very fine fibres were almost invisible when soaked in fuel... It took us a very frustrating week to finally figure out what was happening !!!
Probably an unusual problem as only larger tanks would require baffles ! I suppose the only point worth noting is to be careful with any fittings in the tank such as sender units etc. which could work loose and cause the cheese grater effect.