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Newbie question,

 

I'm building a system and still fuzzy on plumbing,Murray uses a siphon with a 12 minute cycle in his video. "rules of thumb" says 15 miutes on every hour. I understand the siphon idea, but what does the plumbing consist of when you do a timer?Does the bed just drain back through the pump?Different size pumps needed for timer or siphon?

 

250 gal FT,4' x8' x 12" GB and a 1000 GPH pump is what I have ready to get started.

 

Thanks for any insight,

Brian

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Timer based flood and drain systems are predominantly gravity drained systems that utilise a standard "overflow standpipe"....A riser pipe inserted into a drain...

 

The standpipe (riser) has several, usually two small holes drilled in the base just above the drain fitting... this allows the grow bed to begin draining and returning water back to the fish tank as soon as the timer triggers the pump/flood cycle...

 

This minimises the drawdown of water from the fish tank...

 

The outflow from the holes in the standpipe can't drain the system faster than the inflow from the pump... hence the water rises/floods the grow bed... until it reaches the open top of the standpipe.. where upon it overflows directly back to the tank...

 

The height of the standpipe sets the height of the flood within the grow bed... usually about 1" below the media surface...

 

When the timer cycle completes... and pumping ceases.... the grow bed slowly drains through the small outlet holes in the base of the standpipe...

 

This simulates the natural cycle in a soil based system... rain, a flood.... that slowly begins to drain immediately... followed by a period of no further rain/flood... and continuing slow drain past the roots... followed by a "dry" period... (the off cycle of the timer)...

 

Here's a few pics that might help... the last pics show the outer media shroud pipe that keeps the media from falling into the system...

 

If you use a timer, you will use a stand pipe in the bed which has some small holes around the bottom (start small and make the stand pipe removable so you can adjust it.)  Anyway the height of the stand pipe is set to keep the high water level below the media and the holes are sized to let the grow bed drain before it starts to fill again or at least make sure the grow bed can flood before the pump turns off. 

 

If you use a timer, your pump needs to be big enough to move the volume of your fish tank in the period of time the pump will be on each hour at the head height that is required.  So, if your pump actually delivers 1000 gallons per hour at the height you will be pumping, then you could do 15 minutes each hour with that set up.  If you find that your pump is not actually giving you that much flow, you could always run 15 minutes on and 15 minutes off or 15 on and 30 off to get more flow each hour.

 

If using a siphon, generally the pump will run all the time and the siphon manages the flood and drain.  In this case I would recommend a pump that can move 300-500 gallons per hour at the height required and any excess flow beyond what is needed to balance the siphon can be bypassed back to the fish tank for additional aeration.

 

Hope this helps

Siphons systems.. are pumped continuously... they don't (usually) utilise a timer...

 

The siphon is essentially the same arrangement... but (usually) without the holes in the standpipe.. and another capped pipe placed over the standpipe...

 

Adaptions of the siphon utilise a reduction piece... that allows better siphon break with less flow manipulation... google "affnan siphon"...

Thank You for the detailed explanations,very helpful. I understand the siphon and have all the parts to build one but they seem kind of tricky to get working right so I started wondering how the timer plumbing worked and if there were advantages to either one of them.

 

Thanks for the comments,

Brian

Well, BYAP is currently running some trials to compare different methods (trial is only a few months old though) and it seems the constant flood method was able to cycle up the system better and the plants were doing almost as good as the timed flood and drain.  The siphon system was doing between the two in cycling but the plants seemed to be lagging behind.

 

These observations of the trial were a little surprising to me but it seems that the bio filter may cycle up better just running the pump constantly for a time and then the plants will still do well then once the system is well cycled, switching to timed flood and drain may provide even better plant growth while saving energy.

 

In any case, all three methods can use basically the same drain set up with only minor modifications.


Hi to all, another newbie here with the same situation.

My question is, when using a timer, the flood and drain cycle will be limited to the number programmable times. The timer I saw from the local hardware store can only be programmed only up to 8 sequences or times per day. Is 8 cycles enough for a small start up 1:1 system of about 90 liters FT and GB? 

Would appreciate a comment / advice so that I could get the set up started. Thanks.

Best regards,

Bong

  

I would recommend finding a 15 minute increment mechanical timer if you can.  Otherwise I would say run constant flood and just let the pump run 24/7 which will probably cycle the system up faster anyway.

Hola, the 15 min per hour is nessasary to prevent anaerobic conditions from occurring when the gravelbed is acting as the biological filter,it needs to stay aerobic. Throw in some worms to help compost the bed and actively prevent blockage from occurring will keep conditions healthy and happy.

bong sacay said:


Hi to all, another newbie here with the same situation.

My question is, when using a timer, the flood and drain cycle will be limited to the number programmable times. The timer I saw from the local hardware store can only be programmed only up to 8 sequences or times per day. Is 8 cycles enough for a small start up 1:1 system of about 90 liters FT and GB? 

Would appreciate a comment / advice so that I could get the set up started. Thanks.

Best regards,

Bong

  

15 minute per hour is not required.  It is just very common.  People use all sorts of different cycles and the truth is, most of them work.  Many people have siphons in beds that only take a couple minutes to drain and then refill again in less than ten minutes.  And there are some systems that have beds that are constant flow/constant flood and they do well also.  Just make sure there is plenty of aeration and enough flow to keep the bed from going anaerobic.  BYAP is running trials where one system is constant flood another is timed flood and drain and another is siphon flood and drain and all three are doing pretty well to the point that many people are adding additional beds as constant flood.

Comparing continuous flow media beds to ebb n flow microgreens is like comparing apples to oranges.

I'm not comparing to micro greens.  I'm talking about three systems side by side with the same kinds of beds and same kinds of plants.  One running constant flood, another with siphons and another timed flood and drain.

Here is the link

BYAP Trials

decide for yourself.

Thanks TC and EL RAY!

Instead of pursuing the timer, I opted to assemble a siphon. After 2 attempts, I finally got the system filling and draining in about 8 minutes per cycle with pump running 24/7. Happy to report that tomatoes and "kangkong" are doing very well.

Next project will be a bigger system after I complete the hardware.

Thanks again guys!

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