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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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Rupert, my comment about Joel't trial has nothing to do with Joel - this is not a popularity contest.  My comment was to encourage critical thinking.  If a company plans a trial, set's it up, funds it, and reports results that are favorable to the company I believe it is absolutely appropriate to question the results...don't you? I'm sure Joel and you both think this was a perfectly set up and run, and maybe it was, but isn't it ok to question?  Really?

 

Here is where I"m coming from.  When I ran the grow lab at AeroGrow we were constantly running side by side tests.  Dirt vs our system.  Our system vs competitors.  When we were going to use the results in any way that the FCC could get involved - i.e. a claim we would make on TV - we hired an independent person (usually a Master Gardener) to check the test daily, then had to find an expert (usually faculty from Colorado State University) to validate the test design, data collection, and results.  He usually put us through the ringer before he would certify the test results.  And even with all that I can assure you that if we wanted to alter the test results we could have (for the record, we never did).

 

Again, I'm sure that Joel has set up this test with the best of intentions and I applaud his efforts.  We need more and more tests like this!  My point is that we shouldn't be afraid to question the results and we shouldn't assume that this is the final answer.  

I have no problem with questioning the results Sylvia... and they have been posted for all to see...

 

They're also on public display at the BYAP shop... and indeed there are posts from BYAP members that have seen the trial at the shop...

 

I raise the point because from my experience with Joel, I just don't believe that any suggestion or attempt to "manipulate" the results... is consistant with his character...

 

And sorry, but I don't think the way the post was worded was appropriate... or served any constructive purpose... even if your intentions were otherwise...

 

I don't believe that Joel set out with any pre-conceived ideas, although he may have had some personal preferences...

 

And I think that in itself is evident by his post that due to the results BYAP may well advise running new systems with constant flood for a period of time...

 

I can assure you that myself, Joel... and many others... have been surprised, and impressed by the results of the constant flood bed...

Again, no criticism of Joel was intended, nor did I ever say that he "manipulated the results, although I agree that my wording could have been better. My point was that this was a very interesting trial, but not the final word.  As a scientist I'm sure you understand the reasoning I outlined above, so I won't repeat it.  My bet is that Joel would agree with that as well.
Agreed, and let's leave it there Sylvia. I have responded to your PM

Excuse me for butting in on this one Rupert but I see some double standards here.  You have no issue saying that you are "somewhat surprised" at a continuous flow system of mine doing well yet Sylvia may not question a businessman setting up an experiment in which his system looked the better?  What is the difference here?

 

As far as I am concerned, there is nothing wrong with her wording.  I will go further as to say that the debate on continuous vs. timed flow is pointless because supporters of each have obviously found ways to make both methods work.  People will be drawn to the different methods and become supporters of one or the other, as they tend to use one more and more.  You seem to be biast towards people shining up your method of choice, which is fine, but please mind attacking those that question the impartiality of any experiment carried out by a person that advocates only one of the two methods trialled, no matter who they are, especially when you politely questioned the success of my system just a post prior. 

RupertofOZ said:

I have no problem with questioning the results Sylvia... and they have been posted for all to see...

 

They're also on public display at the BYAP shop... and indeed there are posts from BYAP members that have seen the trial at the shop...

 

I raise the point because from my experience with Joel, I just don't believe that any suggestion or attempt to "manipulate" the results... is consistant with his character...

 

And sorry, but I don't think the way the post was worded was appropriate... or served any constructive purpose... even if your intentions were otherwise...

 

I don't believe that Joel set out with any pre-conceived ideas, although he may have had some personal preferences...

 

And I think that in itself is evident by his post that due to the results BYAP may well advise running new systems with constant flood for a period of time...

 

I can assure you that myself, Joel... and many others... have been surprised, and impressed by the results of the constant flood bed...

Cute puppies.

LOLROTF - thank God for Chi

Hi John,
I have the utmost respect for Joel as you know, but I would not rush in and come to conclusions on such a short trial.  We ran ours for 6 months or more. I would have to look back into my diary to see just how long, but it was at least 6 months.

Things change over time.  With our trials on continuous flow, we found it only worked if run with Hydroton or CANNA clay pebbles.  Did not work very well at all using good old 3/4" gravel.   Hydroton and the like allow for a bit of "wicking" effect to spread the moisture around the grow bed.    Also, delivering the water over the pebble surface by the distribution grid promotes water loss via evaporation.  Not important in a mild climate, but in a hot arid climate this would be a major factor.

Just a few more thoughts to share...

Murray, can you help me out with an obvious terminology dilemma that I have - flood and drain on a pump that is always on for me is also continuous flow, or am I wrong?  I have a system with a number of different components, some which are continually flowing (a raft, some towers) and then three gravel beds with auto-siphons.  I have always run the system 24/7, but considered it continuous flow because only the gravel beds have auto siphons.  Is "continuous flow" used strictly to describe a system with a constant volume in the bed - i.e. with a overflow standpipe and no siphon?

Murray Hallam said:

Hi John,
I have the utmost respect for Joel as you know, but I would not rush in and come to conclusions on such a short trial.  We ran ours for 6 months or more. I would have to look back into my diary to see just how long, but it was at least 6 months.

Things change over time.  With our trials on continuous flow, we found it only worked if run with Hydroton or CANNA clay pebbles.  Did not work very well at all using good old 3/4" gravel.   Hydroton and the like allow for a bit of "wicking" effect to spread the moisture around the grow bed.    Also, delivering the water over the pebble surface by the distribution grid promotes water loss via evaporation.  Not important in a mild climate, but in a hot arid climate this would be a major factor.

Just a few more thoughts to share...

Hi Kobus,
"A rose by any other name"   In my mind "continuous flow" means flow into the grow bed 24/7 and exiting via a short standpipe so that the bed does not actually flood as would happen when using a timer or siphon system.  In a continuous flow system there might be a small reservoir of water (say 1") in the bottom of the bed, but the bed does not actually flood. The water just flows right on through....continuously.
That is my definition.....

Kobus Jooste said:
Murray, can you help me out with an obvious terminology dilemma that I have - flood and drain on a pump that is always on for me is also continuous flow, or am I wrong?  I have a system with a number of different components, some which are continually flowing (a raft, some towers) and then three gravel beds with auto-siphons.  I have always run the system 24/7, but considered it continuous flow because only the gravel beds have auto siphons.  Is "continuous flow" used strictly to describe a system with a constant volume in the bed - i.e. with a overflow standpipe and no siphon?

Murray Hallam said:

Hi John,
I have the utmost respect for Joel as you know, but I would not rush in and come to conclusions on such a short trial.  We ran ours for 6 months or more. I would have to look back into my diary to see just how long, but it was at least 6 months.

Things change over time.  With our trials on continuous flow, we found it only worked if run with Hydroton or CANNA clay pebbles.  Did not work very well at all using good old 3/4" gravel.   Hydroton and the like allow for a bit of "wicking" effect to spread the moisture around the grow bed.    Also, delivering the water over the pebble surface by the distribution grid promotes water loss via evaporation.  Not important in a mild climate, but in a hot arid climate this would be a major factor.

Just a few more thoughts to share...

Thanks for the clarification.  Working in isolation most of the time has some drawbacks!  p.s. - I have never even considered the set-up you describe.

Murray Hallam said:
Hi Kobus,
"A rose by any other name"   In my mind "continuous flow" means flow into the grow bed 24/7 and exiting via a short standpipe so that the bed does not actually flood as would happen when using a timer or siphon system.  In a continuous flow system there might be a small reservoir of water (say 1") in the bottom of the bed, but the bed does not actually flood. The water just flows right on through....continuously.
That is my definition.....

Kobus Jooste said:
Murray, can you help me out with an obvious terminology dilemma that I have - flood and drain on a pump that is always on for me is also continuous flow, or am I wrong?  I have a system with a number of different components, some which are continually flowing (a raft, some towers) and then three gravel beds with auto-siphons.  I have always run the system 24/7, but considered it continuous flow because only the gravel beds have auto siphons.  Is "continuous flow" used strictly to describe a system with a constant volume in the bed - i.e. with a overflow standpipe and no siphon?

Murray Hallam said:

Hi John,
I have the utmost respect for Joel as you know, but I would not rush in and come to conclusions on such a short trial.  We ran ours for 6 months or more. I would have to look back into my diary to see just how long, but it was at least 6 months.

Things change over time.  With our trials on continuous flow, we found it only worked if run with Hydroton or CANNA clay pebbles.  Did not work very well at all using good old 3/4" gravel.   Hydroton and the like allow for a bit of "wicking" effect to spread the moisture around the grow bed.    Also, delivering the water over the pebble surface by the distribution grid promotes water loss via evaporation.  Not important in a mild climate, but in a hot arid climate this would be a major factor.

Just a few more thoughts to share...

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