[Billybeau1]

I feel your pain. I have tried about every combination of everything to halt my cyno and bryopsis. The only time I saw my bryopsis and cyno receding was when alkalinity got real low in my tank. It fell below 7.0 for a couple of weeks and I went whow, what is happening. I am now trying to keep it around 7 dkh to see if this has long term affects. I have also decreased my photo period and increased the flow a little in the tank. Any or all of these things could be helping but the jury is still out.

FWIW, when I tried vinegar, awhile back, it got worse not better.

I'm beginning to think it is just old tank syndrome. A tank that has been set up a long time is bound to start having these issues. I'm sure there is another answer, just have not found it yet, no matter how much I read.