Top skimming fueling tank

This is a vehicle fueling tank fitted with a top skimming fuel pickup which ensures only the best quality, most settled bio, is delivered to the filter, and then the vehicle. The tank also has extra valves fitted so that the pump can be used for transfering bio from my primary settling/bubbling tank to this one.

Top skimmer (22mm tube)
How skimmer lays in tank.
Skimmer test in water.
More water.
How the elbows are fitted. The right hand one is soldered to the first extention tube, and the left hand one is free to rotate on a short spigot.
This is a view of the slot that allows the retaining bolt in the elbow to rotate around the spigot. (On a later version I used end feed elbows and soldered an M4 brass nut on instead of tapping the elbow)
Same arrangement on tank connector side.
The foot strainer drilled for stainless bolt to retain copper ball float. End of tube coned to accept filter threaded end. The reason for this is to cut down on the weight of extra conex fittings, as I found with experiments with conex elbows, that they were to heavy and the float was overcome.
Full tank now, showing extended tubes.
The skimmer in action.
Base made from 18mm ply with 2 swivel castors and 2 fixed, of 100mm dia. In retrospect It would probably be better with all 4 castors being swivelling. You live and learn!
Layout of castors giving largest possible footprint for stability.