Good job on the getting new lights and even a tank for them. If anything, they should be fine. They MIGHT even suffer some light shock. Start them at the bottom and find a piece of mesh netting (from the hardware store) and use like 3 sheets of it at first. Slowly take it away sheet by sheet so they get use to the higher lighting. Bang Guy stated in one post that you could start with the lights higher and gradually move them down. I couldn't think of a more perfect time to do that because you haven't gone diggin into your wall as of yet.
These are all precautionary measures and I myself would probably just throw them in there under the new lighting. If anything they might develope vocal chords and learn to say 'thank you', LOL.
When it comes to the sponges, I don't know if you were able to find any pictures or not. They are actually small sponges that "drill" holes into the shells of the clams. These sponges that dig into the shell will look like dots in the hole and be either orange, yellow, green or brown. They come from the family Clionaidae. The whole popping thing sounds a little odd. May just be bubble algae but I can't see any of the pics of the sides.
Here is the kicker with why you may want to search and search for them so you can make a better decision. Because these sponges can eventually take over a shell and cause it to become REALLY brittle to the point where it crumbles after a certain period of time. But there are two ways to get rid of them (one could induce spawning, you would hafe to be careful where you set the clam - once again, that scenario would be based on size). Just make sure that they are indeed developing holes in their shells that are noticeable. Because if that is REALLY the case, either the treatments will kill them or the sponges will kill them or they will recover fully from the treatments.
1. Freshwater dip. This involves taking a smaller tank and filling it with RO/DI water. Raise the temp to exactly where your regular tank temp is. Then use a PH buffer to raise the alkalinity and the PH in the freshwater tank to as close as you can possibly get it to your regular tank. Go to the store and get yourself a HARD toothbrush (not steel or anything) and get prepared to REALLY use it. Once the PH and ALK have stabalized along with the temp in the freshwater tank, put each clam in. They can stay in for a MAX of 25 minutes or around there. Just every few minutes you want to SCRUB the holes in an attempt to get as much sponge as you can and get the freshwater down into the holes as much as you can. This should kill all of the sponges (usually inside of 20 minutes) since the sponges are EXTREMELY sensitive to freshwater.
2. Drying them out. If you take a clam out of the water, they can usually survive for quite some time. They just really slam shut when you do this. Now if you do it, the best way is to find an area where your house or something is nearly the temp of the tank. To cold and you risk shocking them when you put them back in. To hot, and they will most likely start spawning when you put them back into the tank. Basically room temp of about 75 should work. Just pulling them out and sitting them on the bottom of their shells, starts to kill the sponges because sponges hate air. Then using a toothbrush full of freshwater (the same kind of freshwater as mentioned above) once every 10-15 minutes will also kill off more. You just don't want to resoak the sponges as to keep them alive at the same time you are trying to dry them out.
Either way all I can say is good luck on this one. I assume no responsibility from any outcome that happens to these clams; the only reason I say that is because it could be algae or 2-3 other things. I just can't really tell from the pics, so I gave the most common scenario based on the description. If you could get a really clear close up of the side of one of these clams that I can see well, that would help a lot.
