Backyard Aquaponics
A place to discuss aquaponics

Of those of you using flood & drain systems, as a percentage, how much do you allow the fish tank to drain down while flooding? Rationales?

Thanks,

Jim

0%, I cheat by using a CHIFT PIST setup (constant height in fish tank, pump in sump tank). The fish tank overflows to the sump. The pump moves water up to four gravel tubs with loop autosiphons, each flooding and draining independently. When siphon water goes down to the fish tank it raises the water level and pressure, and water flows out the drain to the sump. The drain is an elbow with the inlet at the center of the fish tank, going up to a tee, then over and out the side of the fish tank.

We have a system with 1 IBC (~275 gallons) and 1-100 gallon stock tank (as future brood tank), 11 half blue-barrel growbeds with pea gravel and 2 barrel halves with water for duckweed. I'd estimate we have about 400 gallons overall in the system. The duckweed beds have a slow fill & drain (constant). The 11 growbeds are using bell siphons. There is really very little variation in water level in the fish tank. When I turn the system off, it fills by 2-3".

We weren't sure how it would work... how much water would be drained from the fish tank once we started it up. However, I figured with multiple beds, they would vary on fill/drain cycles and the system should be okay. Once we turned it on and had it running for a few hours, we just filled up the fish tank. We do that periodically based on evaporation or my crazy antics that cause water loss. So far, so good.

I guess maybe I shouldn't be so amazed at all the ingenious ideas here, but I am just the same. I mean, I am in the company of geniuses, right?

Dave, I don't quite understand the last part, getting the water from the tank to the sump. Is that an effort to insure the water returning from the beds is, to a great extent, replacing the more effluent rich water in the tank, pushing it to the sump?

At any rate, your method would mean I would need a sump (another tank). I can do that. And, it seems worth it as it increases the safety and comfort of the fish by insuring the tank always has plenty of water and adding more total water to my system.

Thanks, thanks, thanks!

Jim

Yes, the idea is to move solids out of the fish tank, replacing the poo rich water with filtered water from the beds. Solids will congregate to the center so that's the best place for a drain. In my setup the siphons come in along the edge of the tank to make a current going around, if the current is strong the solids will work their way to the center. Ideally it would be a cone-bottomed tank to make this movement a certainty!

0% also...I have a slightly different setup in that my fish tank overflows into the GBs...there is always gotta be one who is different

Dave,
Do you have a thread for your system, more especially a pic of the way you have your fish tank over flow rigged. I am having trouble picturing it, and have been curious how I am gonna make mine so it will pull the solids out of the fishtank.

Thanks,
Steve

Mine drains a fair bit from the tank, When I set up the timer I wasn't that worried about it. I timed how long it took to fill all growbeds and set to that time (5mins)

ours drops about 1/3

I'm chift pist also - so answer is 0%.

http://www.backyardaquaponics.com/forum ... c.php?t=43

We also use a sump.

If you have enough vertical drop then you could have the sump at the bottom, up to some beds, then the fish tank, then more beds, then the sump. This would make the most of gravity. Having beds right after the fish tank (like Ell and VB) is ideal because you want the solids in the beds. My setup is space-challenged so the fish tank goes to the sump instead of beds.

Hey Steve, the earlier parts of my 2007 system's thread shows how the pipes and things went together:
http://www.backyardaquaponics.com/forum ... .php?t=979

Yeah, but a 1/3 of your tank is twice as large as my total volume

Mine drops about 10%, and when I eventually connect my other growbeds it will drop about 20%. I dont have a problem with this given that the fish live mostly on the bottom of the tank they wouldn't really care what's happening at the surface (unless it's feeding time).

My hydro system drains about 2/3 (66%). My 2 grow beds hold about 349 gallons of gravel and my tanks is a 200 gallon tank. So I guess that the 40% fill figure is about right.

My new AP system is going to be CHIFT PIST.