I’m sure I can remove it quicker than it can spread. Complete elimination may be tricky but I don’t mind a small quantity in the tank.
I love your philosophical approach.
I got some duckweed with baby corydoras. Fish bred by my old fish keeping friend of decades, gifted to me a year or so ago and accidentally/carelessly I allowed a few rogue pieces to get behind my filter intake when releasing the fish, I had never noticed duckweed in his tanks, apparently it hides amongst his guppy grass in his breeding tanks - weeks if not months of frustration followed.
Stages in my war against duckweed:
1 - Removed all floating plants, cleaning very carefully, but not carefully enough. Had therefore a few pieces of hornwort, Indian fern, salvinia and frogbit growing on separately in a large glass jar for some weeks, noticed duckweed in jar, cleaned more carefully and kept fewer mother plants, a few weeks later floating plants had multiplied from the modest numbers I salvaged, duckweed not present on this secondary battlefield. Felt like the not the beginning of the end, but the end of the beginning. Vowed to fight the enemy on the surface, in the hidden recesses and on the beach - well substrate.
This first small victory in the campaign boosted morale but the main battlefield was still seeing enemy action.
2 - Cut all stem plants and leaves of rosette plants to 4 inches below water surface. Constantly checked evaporation line for stuck duckweed - the plant seems surprisingly adept at resurrection after drying out. Ruthlessly netted out all duckweed I could see and, spent ages removing micro bits of duckweed from the net.
Duckweed returned, it had won a small battle.
3 - Repeated above process. And additionally:
Took all piping cables etc., out of tank and cleaned for hidden duckweed.
Waved hands through plants on a daily basis to loosen bits of duckweed stuck (hiding!) in fronds of plants.
Was not winning, 'magically' bits reappeared. Duckweed had won yet another small but frustrating battle. It seemed spontaneous creation!!
4 - Repeated process above, but declared Total War.
Vacuumed substrate, not something I normally do, some pesky duckweed was found lurking hidden between pieces of gravel.
Added an Eheim skimmer, tried first a cheaper model but duckweed eluded the machine. So initially duckweed had another small battle win.
But, with the power of the Eheim and my waves of hands constantly flushing out hidden enemies, and emptying the machine regularly and continuing to wave regularly hands through plants and keep stem plants off the surface, and dismantling and cleaning out all filters - yes some pesky undercover sleeper duckweed was hiding in my external filter and my HOB.
Weeks/months later, declared victory and added my collection of floating plants back to the tank. Church bells rang out, dancing in the streets etc., honestly good luck.
