Draining Time?

[Harold Sukhbir]

Recently i read an article on cycle time for draining grow beds. Apparently they were saying that, depending on the crop, drain times had to be varied. Is this really important?. If so, can anyone suggest different crops and their optimum draining time?

[TCLynx]

Hum, this could be a very simple answer of "it doesn't really mater" but if you are talking about a high tech commercial controlled environment system who's primary goal is the vegetable crops, then perhaps it is more important.

As to specific drain times, I doubt anyone has done enough scientific research into such things to have made a chart to tell what drain times would be best for each type of plant.

What people might be able to tell you will be a more generalized comment like "such and such plant doesn't like wet feet" while others would be happy in a constantly flooded bed.

In general, I think many of my plants are doing better in the grow beds I have that get longer "dry" times but then again. I've got many of the same plants doing just fine in some beds that are constantly flooded.

Don't forget that Aquaponics is a balance and you still need to flood the grow beds enough to provide the needed filtration for the fish and bacteria. Some plants would be fine with the gravel drying out between watering but the bacteria would suffer greatly if you left it drained long enough for the gravel below the surface to dry out.

Truth is, provided there is enough flow and the water is well aerated/oxygenated yet the surface of the media stays dry systems can grow most plants just fine in constantly flooded beds. Most people just work out a cycle time that is convenient and are more likely to vary it by season (because of heat or cold) rather than crop being grown. Most of us grow many different things in a grow bed so varying timing based on plant type wouldn't really work then anyway.

I've also seen debates on if slow fill fast drain is better or is fast fill and slow drain better? To achieve slow fill fast drain, one is usually using a siphon or flout and a continuous pump and the over all timing is based on the flow rates and not all that adjustable and the bed usually doesn't stay drained for any period of time since it is re-filling as soon as it stops draining. The fast fill slow drain with a stand pipe and timer is somewhat more adjustable as to drain time by adjusting the timer and the size/number of drain holes but you don't get the fast splashing (aeration) of the fast draining siphon/flout though the simple action of flooding/draining provides all the aeration needed for the grow bed itself. The fast draining only provides a little extra aeration to the tank the water is splashing into. The constant pumping and flood and drain by siphon probably provides some extra filtration for the system but some plants would rather a bit more "dry" time so it is finding a balance between keeping the fish part of the system happy while also growing enough plants to use the nutrients and provide the desired vegetables.

[Harold Sukhbir]

Thank you for your rather extensive reply TCLynx , just goes to show your experience and concern.

To quote:"Hum, this could be a very simple answer of "it doesn't really mater" but if you are talking about a high tech commercial controlled environment system who's primary goal is the vegetable crops, then perhaps it is more important.
As to specific drain times, I doubt anyone has done enough scientific research into such things to have made a chart to tell what drain times would be best for each type of plant.What people might be able to tell you will be a more generalized comment like "such and such plant doesn't like wet feet" while others would be happy in a constantly flooded bed."

This could suggest an important area worthy of exploiting, as it could benefit the aquaponic domestic and commercial community at large.Through my readings, and i could be wrong as i have no experience whatever, the fast flood and drain time will generally be acceptable for a majority of crops, however, accurate data from trials should effectively improve efficiency as well as production.

I believe if someone post their experience with flood and drain times, for say, tomatoes on this forum, I am sure after some time an overall picture will emerge, saving trial and error and production loss.Eventually a comprehensive list can be developed, of benefit to all. Am i being too forward?.What are your thoughts on this?.

[TCLynx]

If some one has the time and facilities to run the trials it would be great. Of course trials in one location might not really help in another location or season.

Being able to give really good results though, the trials need to be kinda extensive.

Just because a plant does poor in a situation, doesn't mean that it was the grow bed flood/drain time that caused the poor plant. Could be too much shade/sun pests, or a myriad of other things.

[Harold Sukhbir]

Thanks again for taking time to reply and for highlighting so many variables, which i'm now learning are involved, aside from drain times. I guess aquaponics being an evolving science, given time for experience, sufficient knowledge will grow to allow for more comprehensive models to develop. In the meantime, i am happy to be around to enjoy the ride!

[dano]

It's easy to check, just uncover the plant roots and look.When I was using hydroponics [deep well] and aeroponics [spray system] the aeroponics had much more hairy like roots which would use the nutrients much more efficiently. In the hydro system the roots were submerged all the time, and the aero system the roots were sprayed off and on. My current aquaponics system runs for 15 min. every hour which seems to be working great. So I would say that a little dry time is good as a finer set of roots should clean the water better.

[Harold Sukhbir]

Thank you for for showing the difference by observing the roots.I'm almost ready to commission a small aquaponic system and appreciate all this information from both you and TCLynx.

dano said:

It's easy to check, just uncover the plant roots and look.When I was using hydroponics [deep well] and aeroponics [spray system] the aeroponics had much more hairy like roots which would use the nutrients much more efficiently. In the hydro system the roots were submerged all the time, and the aero system the roots were sprayed off and on. My current aquaponics system runs for 15 min. every hour which seems to be working great. So I would say that a little dry time is good as a finer set of roots should clean the water better.