Many people use Sobo 320f power filter. Why? Lets be honest – because it is the CHEAPEST one out there.
As I have mentioned several times in several docs, we need both mechanical and biological filtration in our tanks, at a rate of ~6x lph of your tank’s water volume.
Now, lets look at the Sobo 320f in details.
1. Flow rate – It claims to be 500lph which it is not even close to. Don’t believe me? Take a 1 liter bottle and use your 320f to pump water into that 1 liter bottle. If it is indeed 500lph, it should take only 7.2 seconds (lets say 8 seconds to be fair) to fill the 1 liter bottle. Does it? Let me know how much time it took in the comments
2. Mechanical filtration – Look at the sponge inside it. Its a 3″x1″x1″ piece of very coarse sponge. Not only is the amount of sponge is extremely less (even the smallest sponge filter has more sponge on it), the sponge is very coarse, so only coarse particles will be caught by it, not fine particles. And being so tiny, it will need to be cleaned very often.
3. Biological filtration – The sponge itself is not good enough to host a significant amount of beneficial bacteria. Now, I have seen some people cutting out half the sponge and add 3-4 pieces of ceramic rings inside it. Come on, do you really think 4 pieces of ceramic ring is doing anything at all, specially for a filter that is rated for a ~20gallon tank? Not only you are not getting biological filtration from these 3-4 ceramic rings, you just made it even worse of a mechanical filter by reducing the amount of the already little piece of sponge in there! Even if u replace all the sponge with ceramic rings, u can fit probably 8 pieces in there; however without any mechanical filtration before biological filtration, the rings will be clogged up with debris and wont have space for the beneficial bacteria.
So in conclusion, the Sobo 320f is WORTHLESS as a filter. The only purpose it can be used for is to use it for some water flow in smaller tanks, or to convert it into a surface skimmer or use for co2 diffusion, ABSOLUTELY NOTHING ELSE!!!