Backyard Aquaponics
A place to discuss aquaponics

If you're trying to figure out the void space/ volume - Best way to figure this out is to take a 5 gallon bucket and fill it with your media then see how much water you can add. You can get a ratio of media to water and figure from there. It's going to vary depending on the media you use.

I haven't looked back through your thread to see if the pump sizing is appropriate to the volume you need to pump but your SLO will operate. If any water is coming in then water will be flowing out the SLO once the overflow level has been reached. I like to put a second regular overflow in (one that overflows from the top of the tank) - just in case the water is coming in too fast for the SLO to handle - perhaps something blocks the SLO, then at least the water won't come over the edges of the tank and you have more time to notice and fix it.

the point of my comment wasn't so much about whether or not it would work (i see no reason why it shouldn't work with the right pump), but rather that surely its better to have the water flow from the DWC troughs to the fishtanks rather than back to the sump...

This way the metabolic waste, ie ammonia, would be removed from the fishtanks faster, as the flow through the fishtanks would be higher. Also, the flow-rate through the fishtanks would be equal to the output of the pump, as 100% of the pump output would flow through the fishtanks, some via the DWC, before flowing back to the sump(s), which would in turn make it easier to calculate whether or not your the flow would sufficient for the functioning of your SLOs and bell siphons etc.

Not sure how I would make the water go directly from the DWC into the Fishtank.
I'm open to an explanation on how that would work

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yes i suppose the filter and DWC would have to be at a higher elevation than the fishtanks, and closer to the fishtanks to reduce plumbing

Question regarding sizing the pump for this system.
I believe the general rule of thumb is to circulate the volume of water in the fishtank through the media beds in one hour, but is the same true in a DWC or hybrid system as above.
For example, the fishtanks are 3000l total, so would I need a 3000lph pump or should I take into account all the water in the system, which is approx (3000L fishtanks + 960L sumps + 3600L DWC troughs) = 7600Lph pump?

I'd go with the 3000L fish tank volume as your per hour pumping goal. This would also give you roughly one change per hour of the DWC troughs which is what you want. What I've seen for the DWC troughs is usually in the one water change for every 1 to 4 hours range.

Thanks Scotty.
That's a relief.

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