When I was breeding hypancistrus, I used to created standing waves with an Ecotech Vortech. They were better when used in pairs with one pump as the master and the other pump in slave mode so they are synchronized. However, in smaller tanks, I had no issue creating standing waves with even one Vortech. They are pricey but are amazing. You could always buy a used older model for less. They pretty much last forever…no problems with mine.