Nginx Cache filling up please help!

Hi, I recently setup a web server with Easyengine Nginx Cache + W3TC. It is performing very well, but the problem is Nginx cache seems to fill up very fast (about in a day).

This web server hosts a magazine website, which aggreagates content from various sources, and there are currently about 25.000 posts. Here is the error message I get from /var/log/nginx/error.log:

[alert] 6553#6553: *198911 write() "/var/run/nginx-cache/e/f1/5e175b9fb58aa01c23a706e4f33aaf1e.0000128511" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /en-iyi-arkadasina-asik-olanlar/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com" 2016/08/19 08:21:45 [alert] 6553#6553: *198917 write() "/var/run/nginx-cache/1/60/474354f7a87e990c681fc80be71ab601.0000128513" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /beyonceden-civileme-atlayis/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com" 2016/08/19 08:21:47 [alert] 6553#6553: *198919 write() "/var/run/nginx-cache/1/60/474354f7a87e990c681fc80be71ab601.0000128515" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /beyonceden-civileme-atlayis/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com" 2016/08/19 08:22:22 [alert] 6553#6553: *198925 write() "/var/run/nginx-cache/e/5f/476191d79467b79490937cba63d1c5fe.0000128517" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /yuzu-olmayan-kadin-canli-tablo-oldu/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com", referrer: "http://m.facebook.com/" 2016/08/19 08:22:36 [alert] 6553#6553: *198886 write() "/var/run/nginx-cache/c/cd/329081ce2cbc1b91a96e79c877094cdc.0000128519" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com" 2016/08/19 08:22:45 [alert] 6553#6553: *198930 write() "/var/run/nginx-cache/9/66/77c743612c916b9016e612a7f27e7669.0000128521" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /7-milyon-dolarlik-bosanma/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com", referrer: "http://m.facebook.com/" 2016/08/19 08:22:49 [alert] 6553#6553: *198886 write() "/var/run/nginx-cache/1/9e/d50b248396f2967c1ad45031d8ad09e1.0000128523" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /tag/magaz/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com" 2016/08/19 08:22:49 [alert] 6553#6553: *198933 write() "/var/run/nginx-cache/7/4e/bf5b692acbd5b2319aa9fe8c85e804e7.0000128525" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /ebru-gundes-ten-duygusal-huseyin-utku-paylasimi/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com", referrer: "https://www.google.com.tr/" 2016/08/19 08:23:16 [alert] 6553#6553: *198886 write() "/var/run/nginx-cache/b/f2/a58951386c935ba9a76b8256d6b19f2b.0000128527" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /tag/fitoterapi-uzmani-umit-aktas/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com" 2016/08/19 08:23:17 [alert] 6553#6553: *198953 write() "/var/run/nginx-cache/4/bd/06b1a3ab18cc0620f1b31eb2964bdbd4.0000128529" failed (28: No space left on device) while reading upstream, client: 10.135.13.187, server: magarazzi.com, request: "GET /anil-can-magazin-d-29-temmuz-2016-burc-yorumlari/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.magarazzi.com", referrer: "http://www.google.com.tr/"

How can I increase the Nginx cache size, or anybody know a way to purge Nginx cache automatically, with a CRON for example? Thanks a lot for your support!!