Diesel Additives/Treatments in the Tropics

Good Day All,
When we know the boat will be sitting for awhile, we remove the diesel from the tanks and add fresh diesel when we are ready to move again.  Given the size of our tanks, this can be a costly venture. 
Am wondering what additives/treatments other owners find to be particularly helpful for long term storage of diesel in their tanks, especially in the tropics. 
What do you use and why?  

Thank you!

Debi
Serenity #110

We have always left the tanks full. We have been told this makes it less likely to get condensation in the tanks.

We usually (not always) add a preservative of some kind. I don't remember which off hand.

Upon returning to the boat we thoroughly polish the fuel before running the engine.

For many years we kept the tanks full and added a biocide. But after a particularly boisterous passage to Ecuador we discovered it hadn’t done any good. Growth had proliferated anyway and clung to the walls of the tanks. The banging of the boat in heavy seas dislodged the growth from the walls into the diesel, clogging the fuel lines. Polishing the fuel did nothing to eliminate the growth on the walls. It stays there until dislodged. It’s a conundrum for boats in the tropics for which I am trying to find a solution.
Low fuel level = little growth on the walls, but allows water accumulation
High fuel level = helps to keep moisture out of the fuel but promotes microbe growth on the walls. Add to that the fact that diesel has a storage “shelf life”
Am hoping somebody in the group has an additive which has proven effective in the tropics to address both issues.
Thanks!