Just thinking.....
Will solids build up in the FT due to the pump being in the sump?
A filter will be benefitial, especially if you are planning on tilapia. It will save a lot of work cleaning out the grow beds.
You may need to add supplemental heat for the tilapia.
You can check out Oliver's AP 101 for good information about design and the ratios. http://diyaquaponics.com/forum/viewforum.php?f=112