Enclosed Tezel Surge
I have been using a 5 gallon bucket for the container of my flood and drain tank. Normal, cheap 5 gallon buckets are not made very durable and I have a couple develop cracks on the bottom due to stress of the weight of the water column above it and the weight of the pvc hanging off from it. In an effort to eliminate this stress to improve reliability of cheaper containers, I have altered my surge device to fit completely inside a 5 gallon bucket. This method makes building a flood and drain tank easier by minimizing effort to drilling a 1 3/4 inch hole, cutting two pieces of pipe, and hand assembly of all the parts.
Updated Design:
Below is a diagram of my actual setup with measurements. All pipe is thick walled. I use the Plumb Pak PP830-40L flush valve model from Lowes. A 1.25 inch tee is siliconed inside the bottom of the flush valve. One end of the tee has a plug while the other end has a 1.25 - 1 inch bushing. From there, the bushing has a 1 inch street(spigot) elbow pointed up into a 9 inch length of 1 inch pvc pipe. The top of that has another 1 inch street elbow and a 1 inch normal elbow pointing back down into another 9 inch pipe. The bottom of that pipe has a 1 inch street elbow going into the bung. The bung is made of a 1 inch pvc threaded adapter, a lavatory mack washer, and a 1 inch female conduit adapter. The external conduit adapter has a down pointing street elbow in it.
Additional design assembly:
The only cutting I did was for the one inch (25mm) diameter pvc pipe. There are threads underneath the flush valve but not shown in the picture I found, leave these as-is. There is one bead of silicone around the tee to secure the flush valve and prevent water from entering it prematurely. A tee with plug was used instead of an elbow so the flush valve does not adhere crooked. There is a lavatory mack washer on the screw bung going through the container (its a good size fit). The bung hole center is 1.5 inches from the bottom edge of the bucket (used a 1.25 inch drill bit hole). All parts are hand pushed together, making assembly fairly simple. Turn the top and bottom elbows left/right so everything fits in the container and operation of the float is not impeded. Now push down on the flush valve overflow tube so the bottom line of pipe is slightly angled. You want the plug end to be touching the container. This helps prevent the valve tube end from lifting up too much from bouyancy (causing the unit to not work).
So how does this design work?
The weight of the rubber seal and float of the flush valve keep it seated on the rim of the opening as the weight of the water column above it increases. Once the water enters the top of the flush valve pipe, it begins to equalize levels with the upward siphon pipe. Once the level of the water in these pipes is high enough, it will reduce the weight pressure on the valve seal and release the float, which opens the siphon inlet. Water rushes out the inlet until air enters the flow and breaks the siphon. The float will then close back down to end the cycle. What you do not see is the remaining water in the upward siphon pipe falls back down and fills up the air pocket underneath the valve seal. It does leave a tiny bit of extra air under the flapper which is just enough for it to seal again. The water level in a 5 gallon bucket is less than one inch from the top of the bucket at the time the valve opens and drains but could easily be a lower level in any taller container.
It can be adapted to any taller/larger container.
This design changes the capacity of the 5 gallon flood tank to about 3 gallons which works great for my small system. This design can be adapted to larger containers by adding a 1 inch to 3/4 inch bushing with a 1 inch coupling and additional 1 inch pipe onto the top of the built in flush valve pipe (leave everything else the same).
Caveat: I tried adding a small piece of down pipe to the external elbow (about 2-4 inches). This allowed the water to vortex out pretty but also slowed down the output just enough so not enough water was pulled out by the time the flapper closed so the seal would not take. Adding a much longer piece might work, as a larger water column could have the extra strength required to pull more water out at the end of the siphoning action.
The original design with external piping can be found here:
http://www.backyardaquaponics.com/forum/viewtopic.php?f=8&t=10066&p=284915
And wouldn't you know it, I had another idea come into my head for a "no moving parts" surge that I'm hoping will work better with low flow over a carlson. I'm not getting my hopes high because that's like the holy grail of flood tanks. But I'll at least give it another shot on what popped in my head (you just gotta....just in case...)
, I tried to get an OZ toilet cistern to auto flush for ages without success (well it would flush once,then dribble).