Shop Products
Houzz Logo Print
hiddenleaf

Newbie question about Hydrotron and a F&D system

hiddenleaf
14 years ago

I'm setting up my first system and I have 2 questions

1. I did a test run on my grow bed yesterday and noticed that the Hydrotron was floating as I stirred it with my hands to loosen up any debris. I'm wondering if that is normal for a flood and drain system, or if the water level is too high?

2. I'm not using a timer to regulate how often the bed fills, and decided to go with an auto siphon method. I'm trying to figure out how quickly (minutes) it should fill and then drain? I ask this because I'm trying to figure out how big my pump and the plumbing should be.

Comments (6)

  • hex2006
    14 years ago

    Hi
    You`ll find hydroton will sink after a day or two. Leca expanded clay seems to float no matter how long it soaks for.

  • urbangardenfarmer
    14 years ago

    Is this an aquaponic bed?

    What size is your growbed and reservoir?

    Why the auto siphon instead of fill and drain fittings?

    Sorry for all the questions. Just need more info.

  • hex2006
    14 years ago

    For an auto-syphon you`ll find the drain time will be roughly half the filling time. The flowrate has a fairly narrow range where the auto syphon will work reliably.
    If the inflow is too slow the syphon won`t initiate.. it`ll just trickle endlessly (bed full of water).
    If the inflow is too fast the syphon won`t break when the bed empties and again you`ll get a constant trickle (bed with no water)

  • hiddenleaf
    Original Author
    14 years ago

    Thank you hex. I imagine that if it does trickle endlessly I could just aerate and make it a dwc. What do you think would be an appropriate filling time?. Half that would mean I would need plumbing with an I.D. twice the width of the plumbing that is delivering the water to the grow bed correct? I'm trying to avoid PVC piping, so what do you recommend if you can?

    urbangardenfarmer. It is an aquaponics system. The tank is a 20g tall and the bed is 24" x 12" and the hydrotron is 5 or 6 inches deep.

    I don't want to have it permanently fixed above the tank for water return, and I will be placing the grow bed on a flat surface eventually. So a siphon tubes seem to be the best choice.

    That leaves one last question. How close to the surface should I make the water line?

  • hex2006
    14 years ago

    Hi Hiddenleaf,
    Thats not a very big bed, about 27L overall. Taking hydroton displacement of 50% leaves you 13.5L of space for water. You won`t need a very big pump :)
    The auto-syphon tube will need to be quite small, i`d go for 16mm (5/8") inside diameter.
    Make up a U-tube so when its inverted the top of it is 1.5-2" below the hydroton. The reason for this being water level will get 6mm (1/4") above the syphon tube before it kicks in.
    Position the bottom of the syphon tube so it sits 6mm (1/4") off the bottom of the bed.
    Drill lots of small holes (smaller than the hydroton anyway) in a piece of large (~4")diameter pipe with a few notches in the bottom edge to hold back the hydroton so it can`t get to the syphon.
    The pump size will depend mainly on the lift height but 500-1000LPH should be plenty. You`ll need a way to adjust the flow but from my experiences i would aim for filling the bed in 2 minutes which would equate to a flowrate of 400LPH, but you`d need some extra to account for headlosses etc.
    TBH, it would probably be easier just to fit a 1.5" vertical pipe and drill a 1/4" hole near the bottom (slow drain) and a 1/2" hole near the top about 1.5" below the hydroton level (overflow).
    Put the pump on a timer and run it for 15minutes to flood the bed to the overflow hole. When the pump stops the water drains via the 1/4" hole. You will need the large drilled pipe section to hold the hydroton back with this appraoch too.

    A few options to ponder..have fun

  • hiddenleaf
    Original Author
    14 years ago

    I ordered 40lb or about 50l of expanded clay.
    Thanks for the advice on the pump. I'll look around to see what is available in my area.
    I think I would rather go with a float switch rather than a timer, but there will be no additional filters running the system, so the water has to be a continuous flow.

Sponsored
Ed Ball Landscape Architecture
Average rating: 4.8 out of 5 stars30 Reviews
Exquisite Landscape Architecture & Design - “Best of Houzz" Winner