Backyard Aquaponics
A place to discuss aquaponics

Or.. Ebb and Flow Vs Continuous Flow... What kind of system do you like to have? Why?

Please share your experiences and developmental hurdles while using these systems.

We are now digging for an octagonal grow bed.. dimensions of one side is 5 feet x 2 feet x 1 feet times 7.

I appreciate your time in providing this input.

This has been discusted/debated numerous times over the years. A good side by side comparison is the BYAP system trials. There is no right or wrong and is pretty much a personal preference, some system designs require a certain style too. I've tried most ways except CHIFT PIST and have settled on CF purely for its simplistic design.

Nanni have you tried searching this forum?

the questions you are asking have been discussed here hundreds of times.

Thanks for your input Charlie.

Yes slowboat, read many posts on this and so confused by now.

We have both in our current system but I don't notice any big difference.

I asked again to know your personal preference. Maybe, just vote.

Thanks rupe, on holidays and can't link on my phone

You'll have to do some looking because I haven't gone into much depth here, since it's been done other times.

Major advantages of Constant Flood -

Constant Flood is easier to expand. When you want to add a bed you don't have to increase the sump size each time you expand the system. Just add the water for the new bed and the pipes you added.

The sump can be much smaller because you don't have to deal with the water level fluctuations. You don't always have to have a sump for CF but it means you don't have to top up the system water as often.


Other systems.

Flood and Drain is better at removing solids from the growbeds and probably provides more oxygen to the root zone but I haven't seen any data on the latter. Same is probably true of siphon type systems vs CF.

Most plants seem to be fine either way as you'll see if you look at the BYAP Trials thread.

Size of pump and cost to run are other factors worth looking at that differ.

Great tips there, Scotty. CF is easier to expand... not thought about this one before. This is certainly a big advantage.

I'm going to suggest that neither might be completely true...

Firstly, from my own, and other constant flood systems that I've seen... the build up in media seems to occur much more rapidly than in those with flood & drain...

I attribute this to a constant flood media bed essentially acting as a "settling" tank... as we are basically skimming the water from the top of the media via the standpipe... and the solids drop out of suspension into the media...

Whereas in a flood & drain media bed... the water, and degree of solids... is being either sucked upward and down the standpipe by siphon action... or drained from the bottom of the media bed by the holes in the standpipe.. ala timed flood & drain...

Secondly, while the flood & drain action might inherently appear to provide more oxygenation to the root zone... (and certainly would suggest oxygenation of the system water)...

The same couldn't be said for a constant flood media bed... where the root zone is constantly flooded... yet plant growth appears to be at least similar, or possibly even slightly better...

I believe that is because most of the oxygen up take by the plants occurs from the lateral roots that occur just below the surface of the media... most likely in the moist capillary wicked top 25-50mm... the area which is not usually flooded...

There would appear to be some evidence for this... as, putting aside issues of mold/algae growth... plants in media beds which are a nearly inundated to the media surface... perform badly... just as they do in flooded soil conditions...

It would not surprise me to see certain plants doing better under one method vs. another. Hard to do a controlled experiment, given all the other variables involved.

About the best you can do is determine whether one method works better for your particular system, as everyone's conditions will be different.

Actually I agree with Rupe. I was referring to removing solids from the growbed not holding them in the growbed (a bit confusing I admit since we usually talk about the other).

I also believe that in most cases oxygen levels are adequate for the plants in the growbeds and this explanation makes sense from what I've seen. I can recall where some have added aeration and this helped but these systems may have been overloaded with fish, without sufficient growbed volume, or may have had higher water levels.

The pump will still need to be upsized unless you started with extra pump capacity, can't have everything I guess.

It's been done Jake.... viewtopic.php?p=416912#p416912

One of the plants growing well in our CF is tomato... as Rupert said rightly, roots are more on the lateral surface. It looks like they would outgrow the plants kept in FD in no time.

The BYAP trials... and many members running constant flood... would suggest that there's very little difference in reality...