The first thing I would try to focus on is to provide the most comfortable environment possible for your CSB. I know what I just stated is the obvious, lol, as we all strive to create this kind of environment for all reef tanks, however, I also understand that this is easier said than done. I truly believe by providing the most comfortable environment possible is the key to growing naturally split BTAs. And that can mean a lot of different things for different reefers.
They can naturally split in 2 different ways, #1 stress split or #2 happy split. Whenever the BTAs are under severe stress, they will split naturally to save itself from dying, of course I certainly don't know this for a fact but based on my observation and many conversations I've had with other reefers, we feel that it's a natural process that occurs when the anemone is dying. It's trying to save/preserve itself by splitting in 2 in hopes that 1 of them will survive. Again, although I'm not 100% certain, one thing I can say for sure is when they stress split due to major parameter swings or, perhaps, a major change in spectrum and or intensity lighting or temperature swing, they do not heal correctly, it's because they are under a high degree of stress. They almost look like as if they've been cut which really isn't a good look in my opinion. Ideally, they're supposed to be in a perfect symmetrical circle shape, however, when they don't heal correctly or have been cut, they have more of a lopsided circle/semi-crescent shape look. Furthermore, the cut or area that have split will not connect all the way, leaving a duck feet-like web look. It's supposed to heal and reconnect all the way from one end to another, however, when it doesn't heal correctly, there's almost a what looks like gap that's filled by a new layer of flesh in the oral disc. I'll try to find some samples to illustrate my point here.
By allowing them to happy split in a comfortable environment will not only give them the opportunity to heal correctly, they will also heal quickly. So focusing on the most comfortable environment is key. So I ask, what does that mean exactly? Well, it's something along the lines of using moderate lighting, nothing too high or low, and moderate flow, again not too much or too low, and lastly, moderate dosing = the most comfortable environment possible.
Please don't be offended when I say this but based on the pictures you posted, your CSB does look like it's bleached as the oral disc have lost a lot of coloration. The oral disc for CSBs is supposed to have a turquoise-like green color with a little bit of blue hues, however, your oral disc is almost translucent/clear/no color. This means that it's likely stressed out due to high intensity lighting or high alkalinity, would be a few examples to seriously consider. Zero nutrients could be another strong factor to consider. As far as the high intensity lighting is concerned, it's hard to determine what is good and what is not good for your reef tank because there's such a high degree of variations on what corals, in general, can tolerate. It does seem like the rest of your corals are doing just fine with the current lighting, but at the same time, it could be that they have built up their tolerance to the high intensity lighting, thus, they have adjusted well to your reef tank. By chance, is the CSB the most recent coral (it's actually an invert lol) addition to your tank? if so, maybe it just needs more time to get used to your lighting. I ask because I'm not sure if you got it when it was already some what extra large or you simply grew it out to what it is today. None the less, it's important to provide the most comfortable environment or, at least, a better location for your CSB if the lighting intensity is too high. The one thing I don't like suggesting is to change your spectrum, as important as it is, sometimes it can be detrimental to your other corals which are doing just fine, at the same time, it could possibly benefit them. The question you want to ask yourself when changing spectrum is, "how much risk are you willing to accept?". I'll PM you my spectrum in just a moment. I think one of the biggest problems in reef keeping is that people use too much lighting, so maybe it might be the lighting that's causing your CSB to bleach
one thing you can try is first moving it a bit away from the direct light source which kind what you did already but try moving it a little further, this way it doesn't get a much light as it is getting now. And please do seriously consider removing your torch that is nearby, and or removing all euphyllias from the tank. I understand removing all your euphyllias can sound like a tall order, however, I do believe that mixing euphyllias with CSBs is another contributing factor on why it's bleaching. Again, I don't mean to ask for so much. The reason why I make this point is because, all euphyllias, whether it's torches or hammers, can carry a lot of bacteria and I mean a lot of it. This is why you rarely see a euphyllia and shroom tank as shrooms are typically prone to bacteria infections. Even if the euphyllias has been conditioned for a long time, they can still carry the bacteria. This is why I would never dare put a euphyllia in my tank. To me, that's a big no no. I'm probably going to get a lot of heat for this
If you don't mind, I'll pick this up tomorrow or least by the end of this week as I'm starting to doze off right now lol, sorry.
