3 Trays Benjamin (Filstar XL) also owns a Sunsun HW-302 filter and provided this information about its capacity;
“I found that the Sunsun 3 stage filter that I currently own held about 2 kgs when I filled two of its three trays full with the media.” (Biohome Ultimate)”
This would indicate the volume is approximately 244 cubic inches holding:
Media
Amount Required
Standard, Plus, Mini, Ultimate, Ultimate Marine
2 kgs
SuperBioGravel
3 kgs
Aquatop CF-400UV/Sunsun HW-303B
3 Trays Capacity should be similar to CF-300/HW-302 requiring :
Media
Amount Required
Standard, Plus, Mini, Ultimate, Ultimate Marine
2 kgs
SuperBioGravel
3 kgs
SunSun HW3000
4 Trays
Media
Amount Required
Standard, Plus, Mini, Ultimate, Ultimate Marine
5 kgs
SuperBioGravel
7 kgs
Based on feedback from the Pond Guru who has rebuilt one of these filters.
Aquatop CF-500-UV/Sunsun HW 304B
4 Trays A report from Lori Brooks indicates that 4 kgs of Ultimate are required if three trays are used indicating the total volume available is 332 cu in, requiring:
Media
Amount Required
Standard, Plus, Mini, Ultimate, Ultimate Marine
4 kgs
SuperBioGravel
5 kgs
Sunsun 704B
4 Trays
I have some feedback that indicates the 704B will hold 6 kgs of Biohome Media if three trays are filled indicating total volume of 474 cu in requiring:
Media
Amount Required
Standard, Plus, Mini, Ultimate, Ultimate Marine
6 kgs
SuperBioGravel
8 kgs
SunSun HW-5000
3 Trays
The HW-5000 is very similar to the Fluval FX6. The outer dimensions are nearly identical so we expect it will hold the same amount of media.
Benjamin (Filstar XL) also owns a Sunsun HW-302 filter and provided this information about its capacity;
Capacity should be similar to CF-300/HW-302 requiring : 
A report from Lori Brooks indicates that 4 kgs of Ultimate are required if three trays are used indicating the total volume available is 332 cu in, requiring:
