Yeah 820gph each is alot of flow.
For your 90g right.
Do you have anything else? More phs, or return pump.
If not i would leave them on. As long as you don't see your fish struggling.
Here is a wavemaker timer. Thought you might like it. costs 45 bucks. 100w max each circuit.
In aquariums with live rock and coral, stagnant areas (dead spots) and piles of toxic waste products can accumulate, seriously affecting the health of your tank inhabitants. The Natural Wave™ pump timer creates alternating water currents in your aquarium when connected to pumps or powerheads. These alternating water currents reduce dead spots and keep waste in suspension, allowing it to be more easily captured by filters. Circulation provided by the Natural Wave™ pump timer also stimulates live corals by periodically flushing waste products away. In addition, the surging currents created by the use of the Natural Wave™ pump timer mimic actual wave patterns in the ocean and provide a more realistic environment for your corals.
The Natural Wave™ is a multi-cycle pump timer with six outlets. Two of the three timed outlets have alternate on/off patterns with adjustable periods of 20 seconds to three minutes. The third outlet has a double cycle of 40 seconds to 6 minutes. Connect the pumps of your choice and design the best wave patterns for your aquarium. These outlets provide the optimal flexibility for you to create random circulation patterns. An illuminated indicator lets you know the cycling times. The remaining three outlets are standard power outlets and can be used for accessories such as filters, lights, or heaters
Instructions:
Install three or more pumps in the aquarium at various locations to produce opposing currents. Outlets #1 and #2 alternate on and off so flows from these pumps should be in opposite directions. Outlet #3 follows an on/off cycle twice as long and should be directed toward suspected dead spots.
Each timed circuit can handle up to 100 watts. To control the cycle period, rotate the adjustment knob from 20 seconds to three minutes. Timing the indicator light and adjusting as desired can measure the actual cycle time.
Safety precautions:
The Natural Wave pump timer should be located in a dry location, free from the risk of splash or salt spray. Hang the unit in a cabinet, off the floor to reduce the risk of shock and fire due to flooding or salt spray. All electrical cords plugged into the strip should utilize a drip loop to prevent water from running into the outlet.
Specifications:
The Natural Wave pump timer's electrical rating is 125 volts, 15 amps, and 60 Hz. The timed outlets have a 100-watt maximum per circuit. It plugs into any 110/120 volt grounded outlet and has a 15 amp, push button circuit breaker for overload protection.
