hi, I have been following your thread. Sorry for your losses, totally sucks. Good that you were able to find the cause.
Don't give up on L's. I know (REALLY) it is hard after a disaster to want to try again, but give yourself a few weeks to re-group yourself ,and try again. If you have a q-tank, that would be great, if not, take a real good look at what else is in the store tank, and ask a lot of questions. Ask how long they have had them AND the other fish in that tank. 2 or more weeks is better. But it is never a sure thing, no matter the source, and they may 'credit' you for a percentage of the losses, the last ones they sold you ,but that depends on the store .
If you love them like we do, give it a go again after a bit, and if you can, pick up a small q-tank to give you peace of mind . Hang in there, many of us have been through disasters at some point, but seems many of us dig um so much ,we can't help ourselves and we forge ahead. Personally, I would not have tanks if I didn't have my blue phantoms!
Good luck with whatever you choose.