Backyard Aquaponics
A place to discuss aquaponics

The whole siphon idea to get the water out of the tank sounds scary to me. Nasty point of failure. Not only do you have to be able to keep bubbles out of it and re-start on power failure, you have to exactly match the flow of your upward pump at all times, regardless of turtle-poo-clogs. I also think that the multiple boxes below the aquarium complicate things more than you need.

Here's a picture for folks to start throwing darts at. I think this is pretty simple, and meets your needs. Sorry I couldn't draw any turtles. The template set I grabbed didn't have a half circle, and the turtle looked funny swimming sideways.

Janet- much simpler than the one I envisioned. As you said, the problem with it is penetrating the side glass.

My understanding was that MM has an aquarium, evidently with a stand, possibly an UG filter, and he wants the setup to stay as much as possible the way it is. One other way to give the same effect, (not restarting siphons, etc.) is to put a small auxilliary tank just outside the tank, (like the acryllic boxes that they use in fish stores to scoop water into), extend the lift tube into it (if using an UG filter), (or just a simple inverted U siphon if not), and have your overflow from that work as Janet suggests. Advantage is that it's easier to drill the cheap acryllic box than a glass aquarium, and less catastrophic if you make a mistake. Advantage is that if power drops, the siphon stops (but doesn't break), the GB drains, and the sump fills, but when the power starts again, the sump is pumped, the water in the aquarium rises, the siphon pulls water into the acryllic box, and overflows down into the growbed.
The only issue you would need to be careful of, is if the siphon does break, that your pump won'tpump out your sump, and overflow the aquarium.

Looks good, what sort of biofilter are "you" using in the plastic drums?

E2

Greenedo, Like So?

Exactly, Janet. That way, no drilling, can adjust the water to the GB by adjusting the overflow point. It restarts after power outages, but won't wet the carpet when the power goes out.

It should also stack nicely and not need much alteration for his existing aquarium.
One other thing, the sump with the float switch needs to have the volume such that the water it pumps (pump cutoff point to the top) needs to be greater than GB water volume plus 10% for evaporation, etc.
For example - 50-gal aquarium, 30-gal GB (50% water = 15 gal water flow), if the sump keeps 3 gal when the pump cuts off from the float switch, the sump should be at least 20 gal, leaving 2 gallons of buffer. You also want the overflow to be slower than the siphon, which is slower than the sump pump, (so that the sump pump gets a break). I would also put a small drain in the growbed (1/8" hole in the pipe) so that if power cuts out, the bed will eventually drain, but if things are running properly, you have an AutoSiphon system. (I'm just paranoid about stagnant water).

Sorry for the verbosity. I would say I got carried away, and that it's unusual, but when I get on a roll, my posts can get long.

E2, we used those plastic Bio-Balls as a medium in the plastic drums filled up to about 3/4 full. Due to their design with lots of holes and spikes (incresed surface area) they can harbour a lot of bacteria for their size.

Here`s another possibility.
I borrowed JP`s marvellous drawing and did some tweaking

OK, I get Greenedo's solution, infact i got that far all by myself prior to reading this thread, but how does what hex has drawn work? I am lost

Hi KP
Once the loops are filled with water, the water in the tank will pour down the tube until it is level with the top of the pipe.

The syphon doesn`t break, it sits waiting for more water to be added to the tank like a regular drilled overflow. You could probably make it adjustable
using a short sleeve if its a reasonably tight fit.

It is quite important that the outlet pipe (the one with the arrow into GB) is connected to the drop tube above the level of the first U-bend on the bottom of the tank.

hang on...
water rises above vertical pipe. the pipe fills with water to the level of the tank. Tank overflows.
should the siphon be primed, water fills and works fine. Water drops to below the top of pipe, the pipe sucks air syphon pauses. air bleed allows syophon to unprime... now we're buggered again

perhaps it's the 'connected to power head venturi' that I don't get.

Hi KB

If the level rises above the vertical pipe it pours down the tube, the bottom sump would overflow before the tank. The same thing would happen with a drilled overflow.
You`d need a good pump to outrun the vertical pipe as the syphon has a fair old drop to drive it. You could use 3" pipe if you like

The syphon isn`t broken as the lowest the water can go is just below the tee of the outlet to the growbed which is above the bottom turn in the tank.
Any air from the outlet pipe to growbed rises upwards out of the vertical pipe section.

The pump venturi is just a method to automatically remove air from tiny bubbles that may accumulate over time to form an airlock in the top turn.

so I still dont' get the 'air bleed' where it is placed seems to mean air can bleed in, which will break the siphon... so confused
But really really interested, if you can handle my dumbassedness :-)

Its not easy to picture how it works and i`m probably not explaining it too well either

The only air that can get into the top turn is from the initial priming of the syphon when you install it and also from tiny bubbles that may be carried down with the flow in normal operation.

You install a nipple of some description to remove the initial airlock, a screw-in drip irrigation fitting might work too.
The tiny bubbles may eventually accumulate to create another airlock but if you use a venturi pipe it would suck the air out as it appeared.

In the pic, the white line at the bottom of the vertical pipe in the tank is the lowest water level.
The standpipe would be empty above the line and the pipe would be filled with water through to the tee when the outlet pipe is attached.

oh, so the air bleed is a tap that you open and suck the air through to prime it? very well then. I understand :-) I thought it was open.

The long loop down into the GB does not need to be that long does it? only lower than the loop in the FT right?

this design is almost identical to janets then, excepting that it uses a venturi...
Thanks mate, I got it.

I can`t quite make my mind up if they work the same way or not

With the drop pipe design, water in = water out, any flowrate that is above the white line in the tanks standpipe will force an equal flowrate to the outlet pipe tee, regardless of what pipe size is used.

If you make the bottom loop long enough to rest on the floor it will support itself weight wise, wouldn`t cost much for the extra pipe.

The important thing is the height of the outlet tee in comparison to the loop in the bottom of the tank. If you don`t have enough distance, any bubbles created from the downflow would be easier to push around the bend. I`d place the outlet tee at least 6" above it.