Very Nice man, I dont have anything to add. I have lost a few fish recently myself.
Sorry to hear that. Part of the hobby, unfortunately, is seeing the result of our inexperience at times.
I have had a hard time keeping the water clear, which tells me something is off. I actually reduced the amount of RO/DI water that was exchanged each day because the water was almost "too" clean. In other words, I think some of the beneficial bacteria were being flushed out and allowing toxic levels of NH3 to rise up once in a while. Very hard to figure out the problem, but seems o.k. right now. I actually add beneficial bacteria from a bottle now every few weeks to help maintain the levels. This may also be an issue with the sump not functioning correctly, but I'm going to need a few experts to help me sort that out if it's the problem.
Anyway, I have a list of projects left for this tank:
1. Breed Convicts and Add them to tank, both as food source and as experiment to find hardy fast survivors. Convicts and Plecos are some of those rare fish that can live with Piranha, so we'll see if we can't get a few new tank mates to make viewing more interesting.
2. Make a 8-10" crown for the top of the tank. Allows me to remove plastic that prevents fish from jumping out so the light will enter the tank unimpaired, protects fish from suicidal leaps.
Going to construct of acrylic and paint flat black.
3. Soundproof underneath tank.
4. Finish the cabinet with a removable front and side panels. I'll probably use some rigid foam to provide some insulation and noise reduction, followed by panels of MDF covered in a wood veneer. I haven't decided on the color yet, but it'll be likely Zebrawood or a Black satin. I like the idea of the Zebra wood because it gives me that jungle vibe when I look at it.
5. MAYBE, a system that creates an artificial rain.
6. Whatever crazy idea comes after that.

Thanks for looking and please comment if you enjoy these posts.