One of the comments in an article on growing resistance to herbicides by aquatic plants, notes that "Many of these compounds are too toxic for aquatic use (diuron, trifluralin, etc)...
http://plants.ifas.ufl.edu/aquatics_resistance_final.pdf

I especially wonder about their etc. What are those?

When we poison one thing, we indeed may poison others either with the chemical or the consequences of the poisoning. And if the poison is effective on large amounts of plant material and it all dies, then it will begin decaying. That creates food for a lot of bacteria. In some cases that might suck a critical amount of the oxygen out of the water and could even suffocate the fish or the surviving plants. There are probably other chemical effects of massive rotting of plants or Cyanobacteria - a pH plunge for instance.

If you Google enough, you will find that the broad-spectrum bactericide Erythromycin (in Mardel's Maracyn) will supposedly kill Cyanobacteria. I would council against using it because one may be helping disease organisms to become resistant to the bactericide or antibiotic with enough use; you may cripple the nitrogen cycle (though Erythromycin is less devastating of the nitrogen cycle than some other antibiotics) and lastly; Cyanobacteria may in that context be one of nature's last ways of tying up all sorts of ammonia rich organic stuff in the water before it gets really nasty. Killing all of the Cyanobacteria at once could release so much nitrogen based waste material that you poison your aquarium that way. :(

I am amazed that that company (Canadian, so maybe they are less restricted than US companies are) gets away with marketing that product. These days it seems there is a worrisome pattern where lead paint in toys, tainted meat, dangerous cribs and the like continue until someone blows the whistle. In other areas of enterprise that company makes windmills and pumps which aerate ponds. That aeration is useful in breaking down organic wastes and hopefully preventing large algae growths. I wish they had stayed with that.

I know, in the living room tank I have been struggling with, that if I killed off the Cyanobacteria, I would surely kill off the darters in there. In the thread on Last Shipping of the year we diverged from the original topic when New Guppy Momma complained about the blue-green algae (a.k.a. blue green slime, a.k.a. Cyanobacteria) in her new 10-gallon tank. It is common in newer tanks where biological processes are not yet really well established or where not enough plants are well enough established to effectively out compete the Cyanobacteria for nutrients.

I managed to get sheets of the stuff in an established tank! Not enough water changes, slow growing plants under insufficient light and a rich diet (including blackworms) which contribute a lot of ammonia have made that a mess. I can't believe that several species of darters continue to thrive there, probably because the Cyanobacteria have locked up all of that dangerous crap.

The blue-green algae also doesn't seem to "like" strong currents. I don't know if that is because the current brings more oxygen to the nitrogen cycle - speeding it up, if the b-g stuff just can't hold on to surfaces or what. (But it is a good thing to know about currents and surface agitation.)

You might look back at what I am doing with that aquarium. Basically the gravel keeps getting additional vacuuming and the lights over the Salvinia mat are being left on longer. I may need a second 4" strip light on 12-16 hours and may need to hook up a python water change once a week to draw 50% 0f the water out. Probably could retrofit the strip light with something more powerful if there was the time and cash to do it in the next couple of months.

Ironically some sunlight sneaks into the bottom of the tank. That is not where the floating Salvinia thicket is though. So the sun encourages the Cyanobacteria. Best might be to hang a more powerful light above the tank. That would also allow the floating plants some sunlight because no aquarium hood would block it. The raised lights may generate heat, but their distance allows it to dissipate into the room. If course if the drapes hadn't been taken out, there wouldn't be the issue with sunlight - but the tank might have already crashed.

A similar mat of Salvinia over the bottom tank is working out well. The fish population is minimal. The planting is a lot more heavy. In this case the "natural" response to an imbalance of nutrients and light was hair algae. That is dying back and getting siphoned off.

That room though is our living room and such a hanging light might be impractical for several reasons which have more to do with over-heating the room, not fitting the light with the decor and an inadequate electrical supply to that light itself. So more water changes and leaving the existing light on longer are the best short term solutions - in addition to having effectively change "200%" of the water over the last two weeks and after today, to have scrubbed everything taken out of there of a structural, plant or filter nature at least once.

That water has been dumped in the garden bordering the house. We'll see how that does next spring with all of the ammonia type products in there!

At least the gravel has been turned over and over and hidden dirt deposits hopefully drawn off. Ah nutrient removal! Whatever role the gravel plays in the nitrogen cycle, it has not been set back.

Ah, and a powerhead and sponge filter attachment has been set up in the right rear of the tank. It is aimed left. The in-tank, small canister filter is front left, aimed to the right, also contributing to a circular current.

The only fly in the ointment? There is green slime on that canister filter already! Rats!

It will be whisked out to the laundry sink (carried over a bucket) and blasted on the outside with tap water. If the inside is clear of green-blue stuff, it will be left as is. Then the unit will be returned before it dries out.

Lowering the fish populations and boarding up a window to eliminate diffused sunlight might also help. For some reasons, those things will not happen. ;)

I suppose I should actually be grateful to the Cyanobacteria for rescuing the tank from my neglect. It is hard to feel too grateful.

Your topic is worthy of a log submission. We have ignored logs as something of an obsolete venue. And I missed it because I wasn't looking for any. If Scott L. is investigating new software for GL, including them in the archives may be one of the things he will have to fiddle with. Probably he can just merge lists (databases).

All the best!