I went approx. 60-64 hrs. TOTAL darkness. That means the one and only side exposed to light was covered with 2 layers of beach towel and the other 5 sides are built into a wall cabinet system. Then I did a 20% WC, vaccuuming the top layer of the sand. Then I removed the towels and there was probably some ambient room light that got in for about the next day and a half. Tonight was the first that the lights have been on in several days. I let them on for one hour... I'm actually gonna shut them off as soon as I make this post. No sign of Dino's(knock on wood). All the fish and 2 of the 4 shrimp are confirmed alive, although I think the other two are as well as they're peppermints and probably just hiding. The mushroom rock is very shrivelled up, but I'm expecting it to come around. Tomorrow I'll leave the lights on for 2 hrs, and add an hour each day till it's back up to 12hrs. day. As soon as I see them trying to make a come back I'm gonna go lights out for another 48+ hrs and do the water changes all over again. I havn't been keeping a super close eye on my pH, but I have been adding more Kalk than usual.
Puff, my suggestion is that you gradually build up your lighting rather than just go 6hrs of MH right away. Maybe even start off with 30 min a day and build in half hour steps every day? I'd also def suggest trying to get some Kalk in your system.
As far as no water changes... that makes NO sense at all and unless there's logical reasoning behind it I wouldn't even consider it. The problem is a build up of nutrients, so how would that remotely help out the situation?! It would just allow them to sustain themselves easier when the lights go out, IMO. I think lights out + removal of nutrients(skimming, WC, carbon) + boosted pH(Kalk) is the one, two, three punch that these suckers need to get it through their heads that they're not wanted! Just my $.02, maybe I'm wrong.