Backyard Aquaponics
A place to discuss aquaponics

Here is a thread that talked a bit about them a while back
http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=3057&st=0&sk=t&sd=a

I have since been using them on my aquarium system. (The big aquarium has a hole in the bottom with a regular standpipe type venturi drain but also has a no holes overflow as backup which I have since turned into a venturi drain no holes overflow. The small aquarium has had two no holes overflows that are both modified to venturi types now.)
I have finally adapted them to be venturi drains and gotten some pictures.

Awesome, TCL, I'm about to do the same thing - convert my NHO to a NHO/venturi. These are perfect to get me going.

I don't understand the outlet/bottom picture. Does the water come out of the horizontal section of the Tee? or are there holes down in the gravel, and the Tee is to break a siphon?

the water comes out the horizontal section of the T.
It doesn't actually require the T as one of my others just has the elbow. The extra little bit of pipe is there to balance the levels and help keep it from breaking as I put it in place full. The T allows me to direct where the water flows into the gravel rather than bubbling over the edge of the bucket from the up facing pipe or elbow. You can't have holes down in the gravel as that would break the water bridge and allow it to empty.

They are easiest to do if the gravel bed is immediately next to the aquarium so the size can be small. I have one that has to reach like two feet and it is really difficult to put in place without tipping it too far and loosing the water bridge (while also dumping water all over the place.)

can you talk us though how it works?

A no holes overflow is bassically a water bridge with some extra bits to keep it primed when water drops below the overflow point.

A water bridge is a U shape pipe that is filled with water and placed between two tanks. It will keep the tanks at the same level as long as it doesn't loose it's "siphon" between the two tanks. I'm not so good at explaining, how bout a picture.


Now the no holes overflow is simply a water bridge with some elbows on the bottom of each side so that the water levels in the tanks don't have as much impact on it.

Now here are some diagrams about how the modifications work.

The venturi drain part of the idea just adds a T and another elbow and the pipe to go now near the bottom of the tank.


Now if you wish to direct the flow on the outside bit of the no holes overflow, you can simply add a T there and then whatever you want so long as the flow is always below the overflow level.


Does this help steve?

If one really wants the combination of no holes overflow and auto siphon, it will require another container to house the siphon and this container gets the outside part of the no holes overflow and will need a hole in it for the auto siphon to work. I suppose it might be possible to do this with a very large bit of pipe about the same length as the main tank that one wants to flood and drain is all.

Thanks TCL, I'll be giving one of these a go with the new tank

nice TCL, i only needed the fourth picture, but top job with all of them........you're gonna be the sticky'ed thread queen

I like making handy info easier to find

nice explanatory drawings, thanks, TC
one of the problems of these systems is how to prime them and keep them primed (as there is a constant under pressure situation in the top part of the loop, some gases may develop there)

I have come up with a simple solution that involves an aquarium duckbill non return valve. available at all aquarium shops

drill a small hole in the top spot, glue the duckbill valve in place in the right position, add a length of air hose...
and suck...

has been working fail proof for three months now
every week or so, or if I see that the flow is lessening, I suck again...

excuse the bad picture quality...

frank

Good idea. Was trying to think of an easy way of getting the air out. This type of setup might be a way to keep the bottom of my pool clean. And give me an excuse to have GB's in the side yard to filter out the solids. More morning sun out there as well.

thats great hygicell

hmmm... not good for my so strived after reputation of p*** in the a** though
must find someplace to shock people if I want to keep it

frank

thats alright, even chappo came good after a while

it took him 1000 posts though