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If you are growing using Flood and Drain on a timer, how often to you cycle and for how long?  I think most of us use 15 minute interval timers, so I'm guessing that the duration of a cycle is typically 15 minutes - I know mine is.  I tend to go 30 minutes between cycles if everything is nicely balanced and only 15 minutes between if I'm overstocked with fish and need the oxygen more than the plants need the dry period - which is where I am in 2 out of 3 of my systems now.  The other data point I have is Joel at Backyard says he typically goes 15 on / 45 off with his systems. 

What do you do?  What have you found works best, and what just doesn't work?

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I think one of the determining factors is to turn your FT volume over at least one an hour..... I have a 600 gallon FT and it takes 8 minutes to fill the GB's to the point that the Affnan siphon kicks in, but I run the time up to 12 minutes so I can turn over the complete water volume..... My off time is 45 minutes during the day and 1 hour plus at night.....
That's a great way of thinking about it, Jim. thanks
Uh-oh! I feel like I am back in college and missed this lecture. I run my pump 24/7 and it completes each cycle in about 15 minutes. Can I run it this way or should I add a timer to create off times. What are the advantages? Thanks.
I still have nightmares about doing that... It's not a problem if you are using a siphon or flush valve system which it sounds like you might be if you are completing cycles in about 15 minutes, Greg. Bottom line is your plants need the oxygen that gets pulled through the media when the water drains out, plus the roots benefit from some dry time.

Greg Hershner said:
Uh-oh! I feel like I am back in college and missed this lecture. I run my pump 24/7 and it completes each cycle in about 15 minutes. Can I run it this way or should I add a timer to create off times. What are the advantages? Thanks.
Greg... I understand that a pump will last longer, if you run it 24/7. If your alraedy set up with bell siphons, let it run. Better for the fish too.
true some pumps will last longer if run 24/7... I run a standard pool pump, 81 gpm - 4860 gph... I use a by-pass to bleed off the excess water back to the ST... so my pump isnt made to run 24/7.....

jT
I run my system 24/7 and don't use a timer. Advantages are better water clarity, plant roots continually oxygenated as well as the fish tank getting a regular stream of water from the return pipes and boost in water oxygenation. This creates a certain amount of water movement as well in the tank and fish seem happier (I think) to swim against a current...Some advantages to using a timer system is less of a water temperature drop on cold nights running a timer system (grow beds are a heat sink) this is an advantage if you have warm water loving fish and general energy efficiency.
So, are you using media beds? I am brand spanking new to aquaponics and suffering a bit from analysis paralysis, but it seems I've read it's good for the roots to have a drying out period (for oxygenation??) hence the need for a siphon and timer. I've also thought that by filling a media bed for, say,  15 minutes or so, then draining allows for maximum nutrient absorption and conversion to nitrates.  I live in NEFL, so the loss of heat is not a priority for me ( I don't think...).  The only thing holding me back from building my first set up is the siphons.  I understand the beginning logistics of most of it, but I am just stumped when it comes to building a bell siphon which I assumed was the best for the 12" media bed as it draws out the water quickly. (PLEASE correct me if I'm wrong about this.)   If I could just run a pump 24/7 and use a loop siphon or even a drip system in and out, all my problems are solved!  I plan to start out super small to ensure I have a handle on this before spending $100's and overtaking my yard.  How large is your system and how long has it been up and running? Any tips you'd have done if only you knew??  Thanks in advance.

Frank Gapinski said:
I run my system 24/7 and don't use a timer. Advantages are better water clarity, plant roots continually oxygenated as well as the fish tank getting a regular stream of water from the return pipes and boost in water oxygenation. This creates a certain amount of water movement as well in the tank and fish seem happier (I think) to swim against a current...Some advantages to using a timer system is less of a water temperature drop on cold nights running a timer system (grow beds are a heat sink) this is an advantage if you have warm water loving fish and general energy efficiency.

Hi....

 

as far as siphons go.... I strickly use affnan siphons with timed flood and drain and they have worked perfectly since day one.... here is a link to how I make and install an affnan siphon in a custom growbed..

 

http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=52...

 

starts about half way down the page

 

hope this helps 

 

JT

Allisyn Wood said:

So, are you using media beds? I am brand spanking new to aquaponics and suffering a bit from analysis paralysis, but it seems I've read it's good for the roots to have a drying out period (for oxygenation??) hence the need for a siphon and timer. I've also thought that by filling a media bed for, say,  15 minutes or so, then draining allows for maximum nutrient absorption and conversion to nitrates.  I live in NEFL, so the loss of heat is not a priority for me ( I don't think...).  The only thing holding me back from building my first set up is the siphons.  I understand the beginning logistics of most of it, but I am just stumped when it comes to building a bell siphon which I assumed was the best for the 12" media bed as it draws out the water quickly. (PLEASE correct me if I'm wrong about this.)   If I could just run a pump 24/7 and use a loop siphon or even a drip system in and out, all my problems are solved!  I plan to start out super small to ensure I have a handle on this before spending $100's and overtaking my yard.  How large is your system and how long has it been up and running? Any tips you'd have done if only you knew??  Thanks in advance.

Frank Gapinski said:
I run my system 24/7 and don't use a timer. Advantages are better water clarity, plant roots continually oxygenated as well as the fish tank getting a regular stream of water from the return pipes and boost in water oxygenation. This creates a certain amount of water movement as well in the tank and fish seem happier (I think) to swim against a current...Some advantages to using a timer system is less of a water temperature drop on cold nights running a timer system (grow beds are a heat sink) this is an advantage if you have warm water loving fish and general energy efficiency.
Hey Allisyn.  I'll jump in here and try to answer a few of your questions.  Frank lives in Australia and grows using Murray Hallam's systems from Practical Aquaponics so I'm pretty sure he is using an auto-siphon.  With media based systems you are absolutely right - you want to flood then drain your beds to draw oxygen into the planting beds (although I hear rumors that some people are having luck with continuous flow I wouldn't recommend it for someone just starting out).  This is generally done in one of two ways - with a timer on a 15 minute on and 45 minute off cycle, or with an auto-siphon (a bell siphon is the most popular design of an auto-siphon for APers).  If you use an auto-siphon you don't need a timer...and I think that is what Frank was talking about.  His pump runs continuously because the auto-siphon takes care of draining the beds.  Our company (The Aquaponic Source). is planning on launching a new Bell Siphon product in the next month or so (my husband is putting on the finishing touches now).  Alternatively you can check out Affnan's blog for great bell siphon videos and instruction (he is also a member here so you could send him a message) or Murray Hallam's Bathtub Aquaponics guide also has very good, step by step instructions for building a bell siphon (he is also a member here).  Hope this helps!
Out of demand from my customers I have been building and selling barrel kits. I have been keeping the price low by using cheep materials. I have been using a 15 mechanical timer that is $8 locally. I have a loop siphon along with the timer so that the bed floods and drains for 15 minutes at a time then is off for 45. I added the smallest bubbler I could find(7w) to insure the fish have enough oxygen during the off cycle. The air pump uses far less power than the water pump and the plants are growing fine with this cycle. I prefer loop siphons as they do not take up valuable growing real estate! In small systems growing space is a premium and I cannot justify using any of it for anything other than growing.

be sure and check out the thread on "BYAP Trials" on the Backyard Aquaponics forum:

http://backyardaquaponics.com/forum/viewtopic.php?f=1&t=8621

 

Their testing 3 identical systems except for the draining method:

Affnan Siphon

Constant Flood

Standpipe & Timer Drain (15 on 45 off)

 

The Timer System is destroying the others with Constant Flood not far behind on some plants (mainly leafy greens that like their roots always wet).  Affnan siphon isn't fairing too well - maybe siphoning the water out that fast really doesn't help .  Luckily it sounds like their going to keep the test running for some time to make sure it just isn't a discrepancy in how fast the system gets going.

 

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