Coral banded shrimp died while molting?

[xosux]

Hi,
This morning my coral banded shrimp was on it's back not moving but it's fin things by it's mouth was moving like normal. The back half of it's exoskeleton was gone and both pincers fell off. It did move a little before i left but not much. Some history, i've had it for one and a half years and the water perams are the same then and now. A week ago i bought a fluval fx5 for my 55 gallon tank ( and a 20 gallon refugium ) it works good but puts out a lot of little bubbles all the time. Can the bubbles have killed it and not the other inverts in my tank. Yesterday i went and bought fluval pre filter and some polyester fiber to put in the fx5. I cleaned and rinsed good with ro+di water before putting it in and that puts us up to this morning. Could it be the pre filter or polyester fiber? Any help will be appreciated.
Edit: Update on the little bubbles i have a skimmer that put's out on top of the fx5 return and it is putting the bubbles in and getting spread around.

 

[scrombus2]

I had the same problem with two wild-caught CBS. Biggest one went into my 75 FOWLR and did great for a month. One morning, I woke up to find both her claws were broken off. She retreated into the rockwork for a week or so, could only see her antennae. Then she came out of hiding, with vestigal claws. She molted overnight, I saw her exo in the rocks. She reemerged, both claws fully formed and slowly died over the next 24 hours. Water parameters were (as always) stable. I use natural seawatwer for 30% water changes every 10 days, so I don't think it was lack of trace elements. The second one, in my 20 QT died overnight one night. Any insight will be helpful. I've been able to keep CBS as long as 2 years without problems, but I, too am mystified.

 

[xosux]

I did research on there lifespan and found many in captive live 1-5 years average is 2-3 years here is a link to one of them http://www.fishlore.com/Profiles-CoralBandedShrimp.htm . This makes a little more since considering mine was large when i got it never really growing at all. I don't remember when i got it but it was about 2 1/2 years ago so that's not bad life span i guess. I will try to keep the next one better cared for when i go on vacation as i don't know how the care my sister took.

 

[xosux]

I think i figured it out not. After getting back from vacation my RO+DI was 5ppm so i put new DI in and back to 0ppm. Only a few weeks later and I tested my RO+DI and it was 48ppm after DI and almost 200 before. This meens the DI was taking almost half since my water is almost 500ppm tap ( i know very hard water since it comes from an underground lime and calcium river ). I guess the membrane got messed up not being used for 2 weeks. I just flipped the switch and rinsed the membrane for 1 hour and boom back to 40ppm after membrane and 0ppm after DI. I 99.9% sure that did it since it was molting its body absorbed the contaminates way faster. Man that pisses me off i've put about 30 gallons of this in a 55 gallon tank in a few weeks. Now i will need to do major water changes over the next few days to correct it some.
Thanks