question about filtration

[darkslayer414]

heres the scoop...
i have a 20 gal high tank with a custom built 13 gal sump.
there are about 30 pds of live rock cured in it at the moment and a 2 inch live sand bed.
the tank will have 2 clownfish, 1 goby, 1 shrimp, 10 hermit crabs(maybe more, i like their colors), 10 snails.
as of now there is NO skimmer/filter, there is nothing living in the tank as of now my fish arrive wednesday(20th)
my question is do i NEED a filter/skimmer for my tank to stay healthy, or will it be fine with bi weekely water changes. If i would need more live rock added to the system to NOT require a mechanical filtration system how much live rock would i need to add? I have over 200pds left over from my 100 gallong reef tank that i tore down a bit ago.
any responses would be appreciated. thanks

 

[nissan577]

i really dont run skimmers on small nano tanks. because weekly water changes do what a skimmer does. but if you are planning to have sps then i would use it. but your fish bioload isnt that much at all. so i dont think you would need it.