Ok...I'm still working on my coffee so any calculation errors are not my fault!
Zeolite density is approx 0.8 g/cm3. Make sure you get the granules and NOT the powder.
The area you're looking at is 5 ft x 4 ft, (and assuming a depth of 3 inches). So that's 152x123x8 in cm. Approx 150,000 cm3 (volume)
A 25 # bag is pdz is enough for 11,360 cm3 (25# / 2.2 #/kg * 1000 g/kg)
150,000/11360 = approx 10.5 (25#) bags for 5' x 4' x 3"
Or...if I did this correctly...each full cubic foot of space takes 2 (25#) bags. If you wanted your area at 4 inches deep it would be 5 x 4 x (4"/12") = 6.66 cu ft...so 13 bags at that depth.
I have 100% pdz in my coop and run and it's amazing. As long as you keep it dry it takes less than 5 minutes to scoop the poop and make it look almost brand new again. I use a long handled Brinkman 36" wok skimmer found here:
https://www.amazon.com/gp/product/B004UR1X50/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
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