Tuning a Shadow Overflow

[finaddict]

I finally water tested my new tank today and the oveflow is gurgling LOUD... really loud... 

 

I have my return pump all the way up and the primary drain is draining a bunch of water (water level not over the siphon hole) and the secondary is also draining a medium amount of water.  I have a gate valve on the primary drain line and the secondary drain has flow whether the gate valve is open, medium, or closed.  Any ideas on how to make the primary turn into a siphon and get the secondary to stop draining water?

 

Primary is on the right (top of pictures) and secondary is in the middle and emergency is at the bottom in pictures.

 

 

 

[Jon Lazar]

It sounds like it could be one of two things:

 

- The pipes for the full siphon and the secondary channel are too close together in height. As the water level rises, some of the water starts flowing down the secondary channel before a full siphon can start. Effectively you have two secondary channels, with lots of slurping. Try removing the upside-down U from the siphon channel for troubleshooting and see if that improves things. Based on the picture, I think this is your problem.

 

-or-

 

- The siphon plumbing is undersized for the return pump's flow. In this case you have a full siphon, but it can't keep up and lots of water is going down the secondary channel. Either turn down your return pump, or replumb the siphon channel to increase flow. Use larger pipe, and reduce any backpressure on the siphon channel where water enters the sump. The pipe should be below the sump's waterline, but not so deep that it creates lots of backpressure.

[wildcrazyjoker81]

I had this issue when I had my bean animal setup on my 150G. Jon brings up great points and I too think your secondary is pulling too much water before the full siphon is starting on the first. Close off the secondary 3/4 on the valve and tune the full siphon first. If at full siphon you are getting water down the emergency then slowly start to tune the secondary to adjust to stop the emergency from pulling water. The key with this setup is getting the full siphon started first. I initially made the mistake of having the primary and secondary the same height and that caused me a bunch of heartache if the power went out or I stopped my return because sometimes the secondary would start full siphon and then start to gurgle a lot. To fix it I slightly raised the secondary and it never happened again.

[madweazl]

It looks like there is a hole in both of the elbows; if that is the case, the hole on the primary drain needs to be plugged or it will never go full siphon. The hole on the secondary needs to remain above the water line (in the overflow box) and should ideally have a tube connected to it and set at a height you want it (if what I'm seeing is holes in the elbow, the secondary may have trouble going full siphon when needed unless the water level gets quite high). 

 

The elbows can be set to the same height without issue. 

[wildcrazyjoker81]

It looks like there is a hole in both of the elbows; if that is the case, the hole on the primary drain needs to be plugged or it will never go full siphon. The hole on the secondary needs to remain above the water line (in the overflow box) and should ideally have a tube connected to it and set at a height you want it (if what I'm seeing is holes in the elbow, the secondary may have trouble going full siphon when needed unless the water level gets quite high). 

 

The elbows can be set to the same height without issue. 

Good catch! Didn't even notice the holes until you mentioned it.

[Jon Lazar]

Here's how I set up my beananimal. I used a Ghost overflow at first before building my own overflow box. The method is the same, though.

 

- I set my siphon elbow as low as possible in the overflow box. I left maybe an inch of space between the elbow's opening and the bottom of the overflow box so water can enter the elbow freely.

 

- The height of the secondary pipe defines the normal water level in the external overflow box. I set mine high enough to eliminate the waterfall effect as water flows from the internal box to the external box.

 

- The emergency has to be higher than the secondary. But leave a little space between the top of the emergency pipe and the top lip of the external overflow box so that water doesn't spill onto the floor if there's ever a blockage to the primary siphon. I split the difference between the top of the double elbow and the lip of the overflow box.

 

- Start the return pump. Slowly close the siphon gate valve until the water level in the external box is above the siphon, and slowly entering the secondary plumbing.  You'll have to make very minor changes to the gate valve over the next couple of weeks as pipe friction changes.

[finaddict]

So I went back in and shortened the primary drain pipe inside the overflow box by about 3/4 inch and then seated the u pipe lower. Now the whole u pipe including the hole is barely underwater. The secondary drain is down to a trickle when the primary gate is adjusted. The main gurgling noise is gone but I now have a fair amount of noise coming from the waterfall between the inside the tank compartment,ent and the outside compartment. And I still have a tiny bit of water going through my secondary drain.

 

Should I plug the hole in the top of the primary u pipe and leave the secondary u pipe hole?

[madweazl]

So I went back in and shortened the primary drain pipe inside the overflow box by about 3/4 inch and then seated the u pipe lower. Now the whole u pipe including the hole is barely underwater. The secondary drain is down to a trickle when the primary gate is adjusted. The main gurgling noise is gone but I now have a fair amount of noise coming from the waterfall between the inside the tank compartment,ent and the outside compartment. And I still have a tiny bit of water going through my secondary drain.

 

Should I plug the hole in the top of the primary u pipe and leave the secondary u pipe hole?

 

Plug said hole. If the water level isn't near the top of the primary tube (and I'm assuming not since it sounds like the hole still exists), you can raise the water level in the external box by closing the gate valve slightly. As Jon mentioned earlier, you can further control the water level in the box (to mitigate the waterfall sound) by raising the level of the secondary tube but the siphon in the primary tube gives you a pretty large tuning window regardless of the height of the secondary tube.