Splitting 50-80km dark fibers with CWDM?

We have three dark fibers leased from our ISP, and was wondering how well it would work if we added CWDM MUX/DEMUX to both ends? We'd need one to three connections more between these sites and our main campus.

Can I just get the cheapest CWDM boxes from FS.com or should I consider something else? Which channels should I use?

Current RX powers from the switches:

From Core Optical Optical Temperature Voltage Current Tx Power Rx Power Port (Celsius) (Volts) (mA) (dBm) (dBm) ---------- ----------- ------- -------- -------- -------- site1 35.3 3.21 74.7 2.3 -23.5 site2 34.9 3.21 84.8 1.5 -24.4 - site3 44.9 3.26 29.7 1.4 -18.2 From remote sites: Optical Optical Temperature Voltage Tx Power Rx Power Port (Celsius) (Volts) (dBm) (dBm) --------- ----------- ------- -------- -------- site1 20.3 3.25 1.3 -19.9 site2 19.3 3.25 1.1 -21.0 site3 42.3 3.26 0.6 -17.9 

First two are 10Gbase-ER optics and the last one ZR. Though I'm quite sure the actual fiber run to site 2 is almost 80km... Other two are 60km and 55km from the main campus (just looking from the map, the actual fiber run is of course longer)

Any ideas? Thanks!