Fuel tank

[Celtic Dream]

Hi, on my previous yacht I had a metal fuel tank which I maintained full over the winter months to prevent condensation and bug growth. I drained a portion of it at the start of the season via a sump in the bottom and never had any problems throughout my 25 years of ownership by completing this procedure.
As I have now purchased a Bavaria can you please advise whether I need to keep the plastic fuel tank filled as previous and what do you advise for maintaining it water and bug free ( I do now add bug treatment when re fuelling).

[symphony2]

Never had any problem with condensation (or bug) in Bavaria plastic tanks in the 20 years I have owned them. Mainly I think because I have been very particular about where I get my fuel. However as you don't know the history it might be worth doing what many do and that is sucking out some fuel from the front corner of the tank accessing through the tank sender. The pick up is from the top and the pipe does not go right to the bottom so it is less likely to pick up anything from the bottom unlike traditional tanks which take the fuel from the bottom.

[tiger79]

Yes, as symphony2 suggested, draw a litre or so of fuel from the very bottom of the tank (the inboard forward corner).  I do this every year, after the boat has been stationary in its berth for a couple of months.  I use a simple fuel bulb pump (£9 from Halfords) connected to a rigid tube so I can direct where the pump is sucking from.  It only takes a few minutes.  I pump the diesel into an empty 2 litre water bottle, then let it settle for 24 hours to see whether there's any significant settlement of gunge.  Like you, I always add bug killer every time I refuel.

https://www.halfords.com/tools/hand-tools/all-hand-tools/diesel-fuel-pump-priming-tool-221868.html