Controlsoil is larger granules - which I dont prefer in nano tanks... over 20 gallons, sure.
Pool sand to me takes much longer to cycle and can get 'compacted' more IMO. Also some of it has calcium, which would in fact impact your already high pH.
Personally I like the Eco Complete as the granules are different sizes (small to medium) so it blends better with my nano appropriate fish and plants (fissidens, mosses, riccia, hairgrass, baby tears, anubias, monte carlo, sgitaria).
That said, I use sand (Stoney River White Aquatic Sand) AND eco complete AND gravel in most of my tanks in different layouts.