MidAtlantic area,relatively shallow ponds for production of fry and fingerlings.Usually multicrop each pond:up to 3 times per year each.
Water is pretty hard (120-150),and pH is always on the high side.Out of the well it's 8.3,add a little fert/soybean meal and up she goes,but we've learned to control it with gypsum applications.Don't want to risk raising it much higher.Have used hydrated lime in the past to deal with clam shrimp.
We seem to have two distinct types of water net.One has a very small mesh,and the other is 1/8-3/16" openings.PERFECT for entanglement/gilling of small fish.Mesh size is not related to age of algae.When this stuff comes on,it COMES ON! Is becoming a problem in a growing number of places,and I'm seeing it listed in more and more lists of invasive and nuisance species.

Tentative plan is to hit it just before initial fill next spring with granular Cutrine-Plus,and hope that the concentration at the bottom/water interface remains high enough to be effective on the hydrodictyon,and yet still allow phytoplankton/zooplankton to thrive elsewhere throughout the water column.
We've been fooling around with spot treatments,varying app rates,timing,etc for the last few years.We can kill it.Just can't produce fish in the ponds then.If it takes a year of going nuclear and forgoing production,well then,that's what we'll do.Will have to hit every pond at once,as it's so easily spread.