You did all you could, lets just hope it's something simple as SBD and not anything more serious such as ammonia/nitrate poisoning which is usually deadly.
I suppose if he starts moving around, making an effort to swim and eat then you can say he has a better chance at surviving. Otherwise, if he starts gasping at the surface, goes pale, and overall starts to look worse then I would keep trying and just hope he pulls through..
Just keep an eye on him to see if he sinks to the bottom, then would need to lower the water level.
Hope he is strong enough to pull through, he would have a good home with you. Best wishes to you guys.. keep us updated.