I had the bigger biocube running till just a week ago (santa got me a 105 while the wife was i. China for a month).
I converted it to a sump unit usimg a nano overflow box And. Small ice cap sump in the bottom. My goal was to get a sump on it with as little of modificstion as possible to the biocube.
I had to trim the intake box of the overflow down, but i got it to fit in the first compartment of the cube, with the return going to the second compartment that i turned into a refugium.
I was able to fit everything in the base, it was crowded, but it worked well, and the extra water volumn really helped. (Biggest mastake i made getting in was thinking that smaller tanks would be easier / more stable)
I later took it full trident (had to put the dos pumps on the outside) and this converter it to what i called the “Frankin Cube”
My goal had been to use the cube to “learn” amd eventually go bigger, reusing as much of the tech as possivle.
The sump really opened up a lot of options.
If you go the route of putting things in the base, i would really recomend putting in some lighing first. I put in a cheep stick up light that never really worked well.
Ended up having to do most things holding a flashlight in my teath.
For the 105. I found some new 23 inch LED panels at lowes that are very flat that i really like.
And if your wondering, did i sit in the sump space and just enjoying the lighting for about an hour. Yes, yes i did.
