thinking of a 125g FO... questions

[nanoreefer]

i have a tank that i think is a 125(72"X18WX20H)set up as fresh water with a biult in overflow and a wetdry filter full of pot scrubbers with a queit one 4000 return pump that iam thinking of setting up as a FO tank what eles would i need to get to do it aside from sand, base rock and some live rock? the fish i whant are violations lion, niger trigger, red coris wrasse, snowflake or zebra eel, and a yellow tang would that be ok with weekly 10-20% WCs? i plan on useing mostley base rock so would useing the wetdry be ok for bio filteration i know it would be bad from a reef but what about a fo tank? and sence its going to be an FO tank can i use tap water(from a well)is there any other bad effects besides algea?(witch the YT should keep under control i think)i will also add a DIY skimmer that iam going to make as soon as i find some good plans for one, any advice would be good ive never done a FOWLR or any SW tank over 20g but i figure now is the time and the boxing day sales can only help