Backyard Aquaponics
A place to discuss aquaponics

Higher number higher pressure

Just an idea....

The little holes in the standpipe can get blocked fom time to time.

How about cutting in a vee shaped notch up the side of the pipe rather than small holes?

The angle of the vee could be made steeper or shallower and height of vee could be adjusted to suit drain times.

Just a thought ....

Oh .. BTW ..

Dave Donnelly wrote ..


(All of my ideas come from Dave!) Hee Hee...

My stand pipe have holes (hack saw slots cut in the pipe fitting) in them and they get clogged a couple times a year. Its always the week I dont check every day too.. I lost like 40 onions to this problem last year. I am considering cutting a vee.

I have read Ell's work on bell siphons extensively and although it's brilliant work, I'm a little slower than the rest of the group, thus I have a few clarification questions.

When considering the height of the crenellations at the top of the standpipe, where the cover pipe with cap and air tube go over, can anyone give me an idea what length I should have the crenellations? I'm using standard blue barrel halves with 1 inch pipe as a standpipe and 3 inch cover pipe with cap.

Also should the cover pipe fit flush with the bottom of the blue barrel or should the standpipe be taller than the cover tube leaving space at the bottom for water to enter?

Is the air tube necessary and if so, how do I determine the appropriate placement in the cover pipe in terms of it's distance from the top?

Thanks to all,

TXPower

Hi TX,
I just made the area of the cutouts greater than the cross sectional area of the pipe so that the water flow won't be restricted.

So if we use your pipe sizes:
1" diameter standpipe ~ 3/4 square inch area and ~ 3" circumference

if the vertical cut of the crenellation is 1/2":
3 pieces cutout of the 1" pipe of 1/2" width will give 3/4 square inch area and if spaced 1/2" apart will give 3 uprights for the cover to rest on.

I have my cover pipe about 1/2" off the base of the GB (blue barrel in your case), this is also done to allow sufficient water flow under and up the cover pipe.

The air tube is used to break the seal and fill the cover and standpipe with air after the GB has been drained - what we were finding was that the seal was not being broken and an equilibrium was reached where inflow was equaling outflow - hence no siphoning.

The air tube intake can be anywhere - some have put it in through the top of the cover cap... I put it in the side...both work okay.

The air tube end (other end) needs to be a minimum of 1/2" above the bottom of the cover pipe, it starts to drag in air when the water level falls below it but not enough to stop siphoning until air is sucked under the cover pipe

Hope this helps

My adjustable & removable standpipes. The fact that they slot into a 40mm pipe connector means I can twist them to control drainage flow rates. I have also incorporated the brilliantly simple adjustable overflow control suggested by peterall from earlier on in this thread.



I cut a whole side off as I found just having the "channel" with my inflow rates didn't cut the mustard. Now it gets to the top and just overflows and never moves higher than that.

Awesome explanation Ell, as usual. Nice work Gemmell. Thanks Gents.

TXPower

Ok Ell, got the standpipes plumbed in today, your directions were excellent and I'm off to a good start. Only problem is, the siphon action will not start on its own. I can get the siphon to start by pulling the cover pipe up several inches. I can feel air escaping as I do this, and when I have done it enough and settle the cover pipe back down where it is resting on the crenellations the siphon kicks in and drains like a dream all the way to the bottom of the growbed.

I fiddled with the thing for a couple of hours and no matter what I did, once the water drained out and the growbed refilled it would not start the siphon again and drain.

First, I will remind everyone of the specs on my drain system: 1" standpipe and 3" cover pipe. The standpipe is equipped with crenellations at the top that the cover pipe with cap rests on. When the cover pipe is resting on the standpipe crenellations, the bottom of the cover pipe is elevated approximately 1/4" to 1/2" from the bottom of the growbed. I have an airtube placed in the side of the cover pipe approximately 3" from the top of the cap and the other end is held in place with a plastic ziptie approximately 1/2" to 3/4" above the bottom of the cover pipe.

I have some hypotheses as to why the siphon does not start and stop on its own I want to throw out and get feedback on:

1. The caps on my cover pipe are domed as opposed to flat like I see most people using. Perhaps flat caps on the cover pipe are necessary?

2. I did not use silicone to seal the air tube in the side of the cover pipe where I drilled and placed it. Perhaps not sealing it with silicone allows it to draw air it should not?

3. Perhaps the cover pipe is not elevated above the growbed floor enough?

All help will be appreciated!

Thanks,

TXPower

Not enough inflow of water into the GB is my guess - what size pump are you using and the GB size

Flat or domed shouldn't be a problem and if the gap around the air tube is not too great, then this should be okay too.

If the air tube hole is 3" below the top, then it would be under water as the siphon starts (should start) and would not have any impact in the starting function.

When I make my siphons, I make the outer pipe one and a half to twice the size of the stand pipe (1" standpipe - 1.5 to 2" cover pipe) - so the extra size could be a problem, but lets work on the easy bits 1st.

I have (2) half blue barrel growbeds.

My pump is rated 500gph.

It took quite a bit of force to push the airtube into the drilled hole in the cover pipe. I just siliconed it just in case.

The beds seem to fill ok, but perhaps not quick enough?

I should have stated in my earlier post, the cover pipes would become buoyant as the growbed filled, I'm assuming due to an air pocket?

Thanks Ell,

TXPower

Pump size should be okay then...pipe shouldn't float tho - try putting a weight on it and see if it starts then (temporary measure to locate fault )

Ok, I'll try holding it down tomorrow when its light.

Is it possible my crenellations at the top of the standpipe are not deep and wide enough, restricting water flow, thus inhibiting the start of the siphon?

I'll pop into the hardware store in the morning and get a section of 2" with caps and go that way if I cant get the current 1" 3" setup to work out.

Thanks Ell,

TXPower

The measurements I gave you are the minimum for the cutouts on the standpipe - you can make them wider and reduce the upright widths, but I wouldn't go much deeper with the cuts.

Main thing is not to make too many changes in one go:
1) apply finger weight to cover (and test)
2) make wider cuts (and test)

TX,
now that I have thought about it (floating cover bit), I think the problem is at the other end - how have you done the air trap/"U bend".

The air is pushed out through the trap as the water rises, if the trap is too deep then it takes more pressure to push out the air from bell cover and thus cause the cover to become buoyant.

Will run up a pic of what I mean later

TX, here is an illustration of the air trap and a quick explanation:

1) as the water rises in the GB, the air in the down pipe is trapped and put under pressure

2) the air is pushed out through the water in the air trap ("U" bend) and the water level rises inside the cover pipe

3) water in GB will rise above the end cap and will apply sufficient pressure to push out more air until water then starts flowing into the down pie, siphon action commences and the GB is drained

If the distance "D" is small (mine is about 5mm - 1/4"), the above will happen

If "D" is large (e.g 3"), air will try to push back under the cover pipe and escape into the GB - but before this the cover pipe will become buoyant and start to float

What would eventually happen is the "Bell" cover pipe would rise and let the water start flowing into the drain pipe and eventually kick in...that is if you have enough "freeboard" (navy technical term ), otherwise it would overflow

So what height is "D" and is it the cause of your flotation dilemma

further information of Bell siphons