new 125 with old filters?

[tf]

I am creating a 10' wall in my home. I am building it with a 72"X18"X23" 125 gal. tank in the middle of it. I have checked on the structural integrity and it is fine. It will be right over the baring wall with reinforcments. The question I have is, I have a 75 gal. FO with 25 lbs lr and a fluvol 404 and a seaclone skimmer, with 2-301,1-801 power heads for undergravel filter. I want to lose the UG filter system but use the powerheads, skimmer and 404. Do I need another skimmer? should I also add a 204 or 304 fluvol? If I have 80 lbs of live sand in the tank with the 25 lbs LR will my system need a long cycle time since I am using the old 404 and the skimmer? I will use 1/2 the water from the 75. Will this system work????
Let me know of any suggestions.
TF.

 

[car guy]

lose the seaclone and buy a berlin skimmer, and for a filtering systen i would set up a sump (either wet/dry or fluidized bed) or a refugium, keep the power heads but lose the old filters, thats only my opinion and what i would do

 

[car guy]

also if you do a refugium with lots of caulerpa your nitr. will be at zero, the fluvals are only a host for nitrates, use the ls and lr, and the prexisting water and buy some more lr, it will still cycle but it shouldn't take as long as the intial cycling process