Wah lao bro, the topic of this thread is temperature and you ask flowrate here? A little off topic leh.
Anyway, the flowrate of CL650 varies, some reefers have tried 5000l/h and some tried 1200l/h. I use 2000l/h with no problems.
If you want the reccomended flowrate, I suggest you check out the manual cuz I forgot liao.