I had flux flakes ruin my day at a local contest last month. "New" tank from a commercial source we all use. Started coming out after about 10 flights. When I popped the end cap there was enough junk in there to start a junk yard. My bad for not running a filter (no room, not even for one of the skinny ones) and I had flushed the tank when I got it.
Right. Fuel doesn't touch it, it sticks like varnish on the head of the a Fox 35, until the vibration and flexing shakes it loose.
Part of the problem with commercial tanks is that either fits well, or you make do somehow (like, the tubing comes out at a bad spot and you just work around it). They have to put the tubes somewhere, and the canonical location for the pickup tube is right at the front just like a Veco T21 series. This is the worst possible place in most cases, either it aims right at or hits the back of the cylinder head on profiles, or it winds up right over the engine mounting screws on inverted or upright mounts and leaves about 1" of space for flexible tubing.
The solution is to modify it, so the pickup comes out of the side of the wedge. Then you can get enough length in the rubber tubing to put in a filter. Despite what anyone says, it makes no different at all where the tubing exits the tank. It *does* matter where it goes afterwards.
Most commercial tanks are not cleaned out very well, so filling them with thinner and shaking them up a few times is pretty much mandatory.
...they don't soften, they just linger around the intake and wait till you are level inverted. I don't know how they know but they do. Fuel "cans" can also contribute. Filter everything then do what I did, chicken out and use a plastic clunk tank.
I much prefer fuel in cans, but you can't use the same old can for years, just refilling it, or you will get rust eventually. I like cans over plastic bottles, because they keep light off the fuel, they aren't as prone to damage-induced leaking, and pack in the car well. But you have to keep using new ones, just toss the empties. I also have 4 separate filters in the fuel can pickup line, although I have yet to find more than the tiniest specks of anything stuck in them. The silicone supply tubing gets sticky and falls apart before the filters need cleaning (about 15 years...), at least with Powermaster, SIG, and other quality fuels I have used.
Brett