When I set up my system for Tilapia I found that I had serious peaks in the nutrient levels after feeding. Makes sense if you think about it. Anyway the peaks caused the bacteria in the filtration system to be overwhelmed and I had some mortality. I started feeding the fish using a belt feeder so the feeding was spaced out more evenly throughout the day and the ammonia from the waste didn't peak and the mortality rate dropped. Considering the biomass load in your 100 gallon system the filter you built may experience similar peaks if you feed once or twice a day. My system was a recirculating system with no constant water overflow so filter efficiency made a huge difference as there was no turnover. Belt feeders are aquaculture specific pieces of equipment, not too pricey, but they aren't for pond use so it may not pay for you to try one. just my .02

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