More important than dipping sponges is doing your best not to expose them to air. That can be tricky, getting them from the store (and requesting that THEY don't expose them to air), then acclimating them, then transferring them without getting too much LFS water into your system. I would generally acclimate for twice the time so that I know that 90% of the water in the bag is MY water before releasing them into my tank. Even then, I never had much luck with them.