Backyard Aquaponics
A place to discuss aquaponics

is any one going to PM the man? Or should we ALL do it?

So -you haven't done it yet! (pm GF I mean )

Hope he has the "you have received a PM" email switched on :bom:

have now... :tongue3:

Hi Ell,
Ahhhh, I see your point about the pressure. The caveat is that if the top of your siphon is too tall relative to the back pressure, the top of the grow bed overflows before the siphon kicks in. (Where's the mop?) I had to stop some tests before they got far enough along.

On the last timed test, the GB filled in 9 minutes, and drained in 16 minutes without the pump continuing to run after siphon initiation. Assuming that gravel takes 50% of the volume, I estimate inflow at 166 gph (630 lph) and outflow at 93 gph (239 lph). My inflow tube is 1/2 inch ID (13 mm) and my outflow tube is 3/8 inch (9 mm).

I would feel much better having inflow <= outflow. Right now I am manually turning off the pump during my tests right as the siphon fully kicks in. Eventually, I will go to a timer that works in 15 minute increments. So each pump would run something like ON for 15 minutes, OFF for 45 minutes.

I can do one of two things to equalize flow. Either turn the little knob on the pump to throttle back, or reconstruct the siphons in 1/2 tubing. I suppose turning the little knob would be easier, huh?

Or make a tee and use the excess to aerate with a venturi and circulate the water in the tank a bit. I had a venturi attachment for a little pump around for some reason from somewhere and it's really nice to have the tiny bubbles that come from it.

I think the back pressure would only work if the air volume weren't large. If you're talking about the distance from the top of the siphon to the water surface in the tank that would probably be too large to slow down the water height. I think in order for the air gap to slow down the water rise you would want a second little hoop-de-do just below the bottom edge of the tank. The trapped air volume and water "plug" could then be managed to slow the water height change rate (in theory). If it were just a long volume of air from the top of the loop to the tank surface I think the trapped air would be too much like a "loose spring" to slow the water fill rate.

Oooooo...Venturi. I like that idea. I think I can rig one with a 1/2inch T, a length of airline hose, and a drill. No paperclip needed!

This is turning into a multi-step plan, beginning with the UPS truck pulling up and delivering my 3/8 inch elbows.

1) Get elbows.
2) Reconstruct siphon to include U-turn at bottom and thick-walled 3/8 inch tubing.
3) Test Test Test at full-strength inflow
4) Test Test Test at reduced inflow
5) Construct and rig in Venturi
6) Test Test Test at full-strength inflow.
7) Solve world hunger.

This is going to take a while.

Janet, how do build a venturi?

This guy in the UK is the homebuilt venturi guru:
http://leisure.prior-it.co.uk/diy-build ... turi.shtml

(He's also the reason I've been having my wife buy up scouring pads when she goes to Sam's Club; the pads can be good surface area for biofilters)

Dave, that guy has a really nice cut-away diagram. I had forgotten about the constriction needs, and I'd be constructing at half the size he did. Hmmm, maybe I'll just do a little shower head instead.

Janet, I like to look at worst case scenarios:

Inflow ~ 160gph
Outflow ~ 90gph
Time on 15 minutes, off 45 minutes.
Worst case:
Timer stops pump just before siphon kicks in ie GB full of water
Timer starts pump for 15 minutes, GB overflows (call out the mop brigade)

Possible solutions:
1) have an overflow pipe, but where to put it
2) have sufficient space in GB to take the extra water
3) decrease flow to GB, divert some of the outflow back to tank and aerate
4) increase size of out pipe (knew you would love this one)

Recommendations:
sit down and calmly go through each option available to you
have fun (from your posts you are certainly doing this )

So you tossed away the holesaw for a venturi now

alright Im going for LEGEND...

Here goes

Tadah!!!!

Hi Ell,
Believe me, that worst case scenario has been prevalent in my mind. I am not running the pump unattended right now. Option 1 is possible if I drill or cut through the upper edge of the GB. I like Option 3 the best, though. I think I'll do a shower head, though, not a hand-crafted venturi. This project is at the edges of my tool abilities. Drilling PVC is giving me nightmares. (Any hints? My drillbit always binds up and sticks.)

So here's the really good news: I am getting consistent results with my auto-siphon now. YAHOO!!!! :blob7: :blob7: :blob7: I re-read all the siphon info. I got rid of the wishbone (too hard to tinker with) and turned the white PVC pipe 90 degrees so the brass fitting is horizontal. I then swung the tubing up around in a circle and down to the fish tank. The end of the tube hangs above the water, but has an elbow at the very bottom. I bent the elbow to maybe 45 - 50 degrees. It's now looking very Simmo, but the tube runs at an angle to reach over to the fish tank. The siphon starts quite quickly and firmly now.

I think what might be nice is to actually run PVC horizontally until it is just over the edge of the fish tank, and then drop the autosiphon straight down from there. It's a more stable arrangement that way (I can anchor the PVC to the edge of the workbench), and I might get back use of my workbench drawers. Comments?

Oh, and by the way, auto-siphons were fun fun fun this evening!!! (My beverage might have taken the edge off my earlier frustration, too.)