Backyard Aquaponics
A place to discuss aquaponics

I'm curious if anyone has observed any nutritional and water quality advantages in using a timed F&D vs. a consistent F&D. I know all about how cycling the water once/hr, etc. I'm just curious if the timed method is better for nutrition of plants and water quality.

Thanks,

AquaMissionary

been thinking about that, has anybody done a timed system and found out what the best timing for best plant growth is. i do think the flood and drain with the syphon is a bit to fast. The slowest i can get mine to go is about 23 minuites but that depends on the header level.

I'm pretty sure no one has done the research.

It would interesting to see a study about this. It doesn't seem to make a huge difference in plant growth based on the BYAP trials thread.

Help me out... what is the difference between timed and consistent flood and drain (by "consistent", do you mean constant-flow, no drain cycle)? Isn't anything that floods and then drains by definition timed in some manner?

Yeah think he means timed flow versus constant flow.

I saw it as timed f&d using a timer opposed to using a bell siphon or the like with continuous flow.

Maybe we need a common classification system to avoid confusion

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A friend, seriously concerned for the fish more than plants, found that he had cleaner water with Constant Flood..
He has no problem growing stuff, but could not comment on any small nutritional differences.. CF Vs FnD
Every few days he drains the beds for a time...

I am considering it, because I have developed the feeling that any FnD system, results in clay ball movement that rubs and creates dust and thus turbidity ... I filter using a Canister Filter and likely see clear water to the beds, but the bed outflow is always turbid.. if I fit filter fabric to the outlets, those filters are clogged in a day , with red dust, and need replacement..
The same filtered feed water goes to a DWC tank and that water is crystal clear ...

Naturally, this would not be an issue with heavy aggregate that does not move. IMHO
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FWIW my autosiphon system with hydroton I couldn't cloud up for love or money...

Hi AquaMissionary,

I asked somewhat of a similar question some time back, Charlie pointed me to this thread, i find it very informative thou it might not answer all of your questions.

viewtopic.php?f=51&t=8621&hilit=trial%2A

Hope it helps.

Regards

From memory you were the one who stuffed it up Stuart.

In answer to the thread I would suspect the timed F&D has a slight edge (not because perhaps of a nutritional advantage) see BYAP trials. I am assuming the second was Continuous Flood if it was Continuous Flow I take that back.

That's interesting ... and my water was previously sooo cloudy... but now, after constant flood for 12hrs, I can see fish again... :-)

And I am assuming Continuous FnD , is constantt flood with Auto Siphon drain...
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I'm still confused on terminology... mine had an autosiphon which means it floods and drains, no constant flood.

I did rinse my hydroton before setup. Not meticulously but until it ran fairly clear. But I muck around in there all the time and could read a paper at the bottom of the FT. Maybe I got lucky.

Thanks, everyone, for your replies. What I was referring to as a timed flood and drain system is a system in which the pump is plugged into a timer, i.e. 15 minutes on 45 minutes off. By consistent flood and drain I mean a system in which the pump is continually running. As someone brought up, any flood and drain system is by nature timed by the bell siphon. However, my question is whether or not there is a noticeable advantage in the nutrition of the plants and the quality of the water--in terms of ammonia, nitrite, and nitrate--in a timed (15/45) system vs. a consistent flood and drain system. I ask this because it seems to me that if you allow the water to stand in the grow bed for 45 minutes it would give the plants more time to pull the nutrients out. Thus the plants would grow better and the water would be cleaner. I currently run mine as consistent flood and drain because I like the oxygenating effect it has on the roots and the water, and because I don't want to cause unnecessary damage to my pump. However, if there are nutritional advantages for the plants I might consider making some adjustments.

AquaMissionary