Well, Bryopsis is a NASTY weed in home aquariums.. it's something all aquarist hope to avoid in home aquariums as unlike hair algae, which has the same spread rate, nothing really controls bryopsis that well.
Bryopsis, like most nuisance algeas.... come and go.. it's something that grows in newer tanks when the system is less stable and holding a lot of phosphates and/or silicants. Having bryopsis means poor water quality as it's thriving in those conditions. If you're tank is pretty established, chances are bryopsis is going to have a die down as it's starving of food. Then you can finally rejoice!... or in this odd contrary scenario struggle to keep it alive.
Let's look at how you CONTROL bryopsis, and consider what conditions you need to avoid:
Bryopsis fades in:
Low Nitrate
Low Phosphates
High magnessium (how I beat mine)
Low Silicates
Protien Skimmer or UV sterilizer
Now look at those, and reverse them..
to grow bryopsis, you would need:
High Nitrates
High Phosphates
Low Magnessium
High Silicates
No Skimmer or UV unit
... Yeah I don't think anybody in the tank would be happy with those conditions. It's kinda beating a dead horse purposely trying to make bryopsis. It's a very difficult thing to do, a noob in the hobby would have an easier time maintaining bryopsis doing things wrong than an expert aquarist would doing things right.
Now, theorectically your nitrates, phosphates, etc aren't harmful while the bryopsis is in the tank.. people always get a reading of 0 nitrates whenever the algea and present and continue denying it's their water quality, when in actuality, bryopsis (and other algea) SOAK up all the nitrates. The lettuce slug is technically in a 0 Phos, 0 Sili, 0 Trates environment, because the high bioload and rapid increases in nitrates is what's feeding the algea and being used up before it's harmful. You can keep lettuce nudis with bryopsis in those conditions despite their fraility for those reasons. However if your tank is already established... triggering a second algea bloom might not be a great idea as it's not sucking up all the nutrients immidiantly until it spreads.. (you'll likely trigger hair, diatoms, cyano, and dinos before bryopsis anyway. Bryopsis is the rarish weed in comparison to the others.)
