Got the replacement Eheim Jager Aquarium Thermostat Heaters in a day or two ago. These are 200W instead of 300W, and about 2" shorter. I can now fit them in the sump and fully submerge them.
The new heaters are in place, but not plugged in. Need to read the InkBird thermostat controller manual and make sure I have it setup right for both outlets. Then I'll straighten out some of the wiring and pull out the old heater.
One other thing I (re-)remembered... heaters have to be "in the flow". I couldn't figure out why the tank temp kept fluctuating, then I remembered this. I moved the original heater into the return chamber and the temp stays pretty steady now. With the two new heaters positioned where they are now I think my heat issues will be completely resolved (fluctuation and overworking the single 200W).
I also ordered a couple 14" 200-micron filter socks and a new filter sock holder. The filter cup that came with the setup doesn't really fit in the holder, nor is it deep enough to allow me to put anything in it.
Not sure if I mentioned it before, but I tossed all the "Life Rock" pieces I won at FFM into the sump. Figured it was better there than just sitting in the basement doing nothing. Additional bacteria foundation, eventual pod hiding places, and will eventually use to mount frags for DT placement or sale.
The only other change is the addition of two Banggai Cardinals. Not sure if they are male/female but I've got my fingers crossed. When they went into the tank they get separated. A day or two later they found each other again and have pretty much been inseparable.