Backyard Aquaponics
A place to discuss aquaponics

It seems most systems here use flood and drain and am curious as to why.

I'm setting up a system and would like to avoid flood and drain. It all seems a bit tricky, with the auto syphons etc. and there are long threads with ppl trying to solve problems with these.

I'd prefer to use a trickle system on a timer, what are the disadvantages? Am I missing something?

You can flood and drain without using auto siphons if you want. You just set up a slower drain than the pump (make sure the overflow can handle your pump flow just in case the timer isn't perfect.) Run the timer long enough to flood the bed quickly and then while the pump is off, the bed will slowly drain.

The benefits of flood and drain are that the gravel (except for the very top) gets evenly wetted, allowing the bacteria the best situation for doing their job. It also helps distribute solids throughout the bed rather than just where the trickle happens. It avoids the drawback of small holes or drippers clogging up with solids. It allows for great aeration of the water and the media without extra bubblers in the grow bed area. Media beds serve 3 main purposes, supporting bio filter bacteria, providing solids filtration and being a great place to grow plants. Flood and drain seems to support all these the best without some of the drawbacks of trickle or continuous drip.

With trickle, the water tends to pick a path and leave the rest of the media dry and therefore not supporting your surface area for bio-filtration. And of course the biggest reason not to do drip or trickle is that you then have to keep lots of little holes clean of the solids you really want in your grow beds.

+1

+2
A good explanation TCL.
Timers with 15 minute increments are cheap and reliable IMHO.

+3 Thanks,

I thought these might be the reasons.I've got the 15min timer, so I'll make the changes.

Flood and drain is not at all difficult if you trial the flow rates, and sort out the fittings you need before building the system.

I have 18 syphons that all work perfectly

Cos they work so beautifully.... with minimal supervision once established

And your system usually does not end up fully drained every cycle, mostly the syphons stay out of sync = better fish tank level.

I've got lots of siphons, I've used at least one of each kind I know of. The only situation I've run into where I didn't have the patients to get the siphon to work right was when using a half barrel. Since the lower levels require less water per dept compared to the upper parts, getting the flow rates perfect when using small pump/small siphon, it was just too tricky to balance. That bed now gets filled by a little pump on timer and slow drains. The rest of my siphons have worked perfectly. I've even got one flout running and that is actually my favorite since flow rates don't need to be as balanced. But the flout takes more space and is a little trickier to build.

Oh, and I have one huge grow bed that I actually installed a sump pit with sump in it. I like that one pretty good too.

Autosiphons Rock!

And as OBO points out, the beds don't usually synchronize, so water level in the fish tank fluctuate less.

Do plan on the siphons occasionally all working together though and plan your volume accordingly.

I have tried every from of hydroponic growing. Flood and drain is the most reliable and most practical. It provides surface area for bacteria. It is also most reliable, plants do not die just because of a technical failure for a few hours and you do not have to tie up your plants. You can read a little more about my trials http://66.76.55.66/naphtha/hydro/hydro.htm

Flood/drain is problematic since it requires lots of extra water: either a sump or a high ratio of fish-tank to grow-bed (you are combining tank and sump as I see it.) But, it beats trickle for reliably getting water where you want it unless you have troughs or tubes to make sure the water gets to all your plants and gravel.

Auto siphons are great if you have enough fall for them to work reliably, but do tend to finish while there is still some draining to do, especially when solids build up and the gravel drains more slowly than in the beginning. One advantage of these is that one can have the pump run 24-7 and avoid the wear and tear of starting it up. The problem that crops up from this is that these less-powerful pumps running continuously can clog, but a timer that turns off once each day for a short time would allow the backwash to clear the pump intake.

Timed pumps work well, but some have concerns that starting the pump so often might cause them to fail from electrical current surge.

The Barrelponics flush valve is really nice: allows a good long waste cycle while water drains, but it takes up some space. It does not require the drop that autosiphons need, though: more like timed pump systems in that respect.

It might require more water, but requires less growbed space.

My syphons have no drop at all?? They finish straight from the bottom of the barrel, into a common drain.

For an initial system, continuous flow is the way to go

Systems 2, 3 ,4 5 and 6 would probably be syphons, just due to how good they are when built properly.