Backyard Aquaponics
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Hello to all. I am starting to build a flood and drain gravel bed adjunct to an existing raft system . The estimated gravel volume of the bed is 500 liters. My questions are:

1. How much water is needed to fill up the the gravel bed ?
2. Using a bell siphon, what would be good rates of inflow and drain out ?

Thank you.

I think these 2 are the same.
I have 9 l/m each bed

I think the usual estimate for the amount of water needed to flood a gravel bed is 40% but I like to judge that I need 50% so I'm sure to have enough water capacity in a sump to deal with it or to make sure I'm not running the fish tank level too low while flooding.

The Inflow you need into the bed is gonna depend on the size of the bell siphon or your bell siphon size needs to depend on the flow rate you will supply to the bed. There are some siphon threads in the Hardware section that might be able to tell you the flow rates for different size bell siphons so try doing a search.

TCL have you measured the flow you have?
For me as I said 9ltr/minute per bed...

I have not measured my flow into each bed but I'm mostly using loop siphons. I used to have 1 inch ID tubing but Now I'm using 1 1/4 inch sump pump discharge hose.

Oh yeh sorry for the gumby question

Thanks TCL. 40%-50% ? So, filling the bed with 250 liters would not be a problem for the 4000 liter raft system from where I intend to draw water. Okay, I will experiment with the flow rates. Thanks again.

I used .375 inch / 0.9525 cm smooth river gravel and it took almost exactly 33% of the container volume to fill. So it varies with rock size.