Place them in different places and direct the water to the inlet of the filter. They are great for tank circulation. Not only do they give your fish a "treadmill" like flow for "exercise" and swimming, they also direct all food and fish waste to the filter inlet if you can position them correctly. Not too strong, not too weak. With all 4 in 75 gallons they work great. 2 months and no problems.
KEDSUM 330GPH Ultra Quiet Submersible Pump With High Lift And Grounded Power Cord - Ideal For Fish Tanks, Ponds, Aquariums, Statuary, Hydroponics - Includes 3 Nozzles And 1500L/H Water Flow
39 Review
Sink filter Prio New Water Start Osmos OU380 white
79 Review
KEDSUM Quiet Rechargeable Battery-Operated Aquarium Air Pump With Dual Outlets - Perfect For Fish Tank, Outdoor Fishing, Transport, And Emergencies
28 Review
Powerful And Quiet Submersible Pump For Aquarium, Pond, And Hydroponics: KEDSUM 660GPH Pump With 6Ft High Lift And 3 Nozzles
29 Review
π U-BCOO Aquarium Gravel Cleaner Fish Tank: Manual Siphon for Efficient Filter Gravel Cleaning and Water Change in Tanks
22 Review
Efficient 2-In-1 Magnetic Fish Tank Cleaner With Non-Slip Design And Scratch-Free Blades
37 Review
Jasonwell Magnetic Aquarium Fish Tank Glass Algae Cleaner - Floating Brush (L Size)
37 Review
Vacuum cleaner TEQQO Aquastick 3 in 1 Power, grey/turquoise
26 Review