am in the procces of building a indoor cage for a male Ctenosaura pectinata. the dimennsions are 48/48/30> it has a 6 inch lip around the bottom of the cage to hold subbstrate in i also have a large log sitting diagnoly in the cage. i have a few questions tho 1. what should i use for a substrate i was thinking a sand decomposed granitte mix
Depending on where you live and availability, Cypress mulch works well. The sand and granite would be nice for digging burrows but only 6 inches of substrate will not allow much digging.
2. also how large should i make the hides or should i make a very large stack hide(witch i am leaning towrds)?
A stack would work but most of my Ctenos enjoy hiding up high in their enlosures. Hollow cork bark tubes positioned near the top work well. I also use the 6 inch corrugated black plastic drainage tubing. They really like those.
3. also i have read conflicting advice about cliping nails of iguannas
Of course they prefer not to be clipped but if you want to handle the iguana frequently you can clip or wear protective clothing. I don't clip most of my Ctenos except the really well socialized ones that are used for education.
4. also do female iguannas have infetile clutches?
Yup, sure do.