These products were tested a while ago, and Startron, Grotemar and Marine16 won.
Soltron didn't figure it was so ineffective. However, friends of mine use it and haven't had the bug. Perhaps coincidence, or maybe it does 'prevent it' without actually killing an infestation!?
I will say however, my twin tank setup on the Scand has a problem over the last year, where with both fuel feed and both fuel return taps open, one tank would always fill up over a period of hours, but a week after adding Marine16 I can now open all 4 taps, and the tanks run evenly with no bias.
I therefore conclude Marine 16 did something effective!
I used marine 16 to kill bugs in one of my tanks, worked well and I was surprised there was no residue of dead bugs in the filter after. I was given a large quantity of very old buggy diesel and again the marine 16 products got rid of the problems and made the fuel perfectly usable, saved me a lot of money!
Didn't work for me. I built a DIY filter from a CAV filter and a 100lph facet electric fuel pump filtering the fuel several times a year with nothing showing up in the filters. The engine water separator was similarly clean with perhaps 1/4 teaspoon of silt a year. This is what I found when I opened up the 25 year old fuel tank out of curiosity. I don't know how long the DB has been there, I have owned the yacht for 7 years. The consistency of the DB was similar to custard so I scrapped the glup out with a 2" paint scrapper. The filter was run from the water trap at the bottom of the tank and returned to the fuel filler. However, the DB consistency meant it just sat there rather than be moved around and into the filter. The tank was dosed with one of the DB killers at each fill but I have now switched to Marine 16.