From "Futuredoc"
www.thereeftank.com
Bryopsis? Lowing nutrients helps but they are very resistant in low nutrient systems so a LNS does not always work.
46g, the best solution is Kent's TechM. TechM is a magnesium supplement that has an impurity in it that is deadly to bryopsis. Often it is assumed that the Mg is doing the killing but that is not the case. I have fought bryopsis for a long time in several tank and this is the only known "bottled cure". Here is the directions.
1. Buy 3 16oz bottles of Kent TechM (no other brand will do)
2. Do a 20% water change.
2a. If the bryopsis is high in the tank (on overflows of pumps) and is exposed while you are removing the water, pour some TechM on the bryopsis if possible and then add new water)
3. Use one entire bottle of TechM... all of it. Save the other bottles for two weeks. Within the next two weeks you will see bryopsis dissolve slowly.
4. After 2 weeks, do a 20g water change and add another bottle of TechM to the tank.
5. After another 2 weeks (4 weeks total) do a WC and then add the last bottle. You should be good after that. You need to keep nutrients down by not over feeding and doing quality water changes using NO3 and PO4 free RO/DI water. If you start to see any bryopsis spurt back up... (once fish stores have it, it is easily reintroduced back into the home aquarium) have TechM ready and dose a bottle immediately. This is completely reef safe as I have done this in my SPS systems more than I would have liked.
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Clemson Ph.D. & Mary Washington Alumnus