One of my crayfish hasn't molted in over a month

[BigB322]

Hello,
I have two crayfish one is an electric blue crayfish, and the other is a bright orange crayfish. They are both in the same tank 10G (till I get the bigger one set up) and the electric blue crayfish hasn't molted in over a month. The Orange one has molted 3 times each about 2 weeks apart. I got them about a week apart. The blue ome is about 2" and the Orange one is about 4". The tank has multiple caves/rocks, some driftwood, and sand substrate.
Temp: 75°F
Ammonia: >1ppm
Nitrite: >1ppm
Nitrate: >3ppm
Ph: 7.5
2 times a week 20% water changes
They eat pest snails like candy and I feed them a variety of carnivore and algae sinking wafers.

 

[qldmick]

I wouldn't be worried. My Cherax albidus are medium/small and are moulting about every 6 weeks but I've had a redclaw crayfish that molted like 4 times the amount as the other redclaw in the tank.