how many bpm should I be getting from my DIY System?

immune

I am currently getting about 23 bpm in my 75 gallon tank. I have another DIY canister system I can put in if that is not suffiecient but I wanted to make sure that it would not kill my fish ( a juvie bristle nose pleco and and a juvie albino tiger oscar.my tank currently just has Babys tear and Subwassertang. I would like to run the system in such a way that I can get a lot of growth out of the Subwassertang quickly as I bought it on an online auction and did not receive much. My substrate is 1 inch lava rock 2 inches or fluorite red and 1 1/2 inch sand. The surface tension is low and the temp is at 78.