One thing, can you shade it at all? So then you dint have to change the lighting, but you will have less direct light hitting it?
Second, I would try to feed it at night when its opened. When mine are struggling, I will feed them at night some mysis and I have yet to lose one all the way. I also use squid, if they get it in, it works well, but they can be really picky towards the squid.