Overflow "Chugging"

Why would a 1" overflow pipe be a problem on a 29 gall tank if I have a ball valve on the overflow pipe? When I was building it everyone said use a 1" pipe for the overflow.

 

The 1" pipe is fine, I use it on my 90 with no problem. extend the overflow pipe so it's underwater, I actually add a 45 deree elbow on the end of that as well. you only need to get just below the surface, no need to go to the bottom with it.

 

Generally speaking restricting the overflow pipe is not a very good idea as the potential for flooding is increased.

Let me see if I can relay my experience as the issues I had seem to be similar to the ones you are having.

I too have a 29 gallon tank, however I use a HOB overflow and not a drilled overflow. The problem was that the overflow is rated at 300 gph but with a 10 gallon sump I do not want to circulate 300 gph, so my return is throttled to approximately 125 gph. When the overflow is not running near its capacity the result is usually noise. With the drain below the surface of the water I would get a lot of belching out of the sump. As the column of water in the drain plumbing gains sufficient mass to overcome the back pressure of the water in the sump it quickly empties itself then has to refill enough to overcome...I think you get the picture, lots of belching and noise from the sump.

So the initial solution was to raise the drain plumbing above the water line which eliminated the belching but created major problems with the spray and splashing from the cascading water.

So finally I constructed the afore mentioned "Splash Box" which seems to be the way many commercial sumps have the drain section constructed. This by far has been the most elegant solution.

So in short it sounds to me like you are experiencing problems because your overflow is running below its capacity. To remedy this one solution would be to increase the return flow to be near the capacity of the overflow which for a 1" pipe is approximately 600 gph.

 

I don't think that is the problem. I have a 600 gph overflow from glass holes being fed by a 125 gph pump and its pretty quiet. Sounds like trickling water, there is no gurgling or anything.

Instead of hard PVC I am using flexible hose and instead of going straight down it slopes so the water runs down the hose and gently trickles into the sump below the water line.

 

You are on the right track. I have the Mag 7 on my 55 gal. so play with the out flow. I have the Megaflow 1 sump and in its' design the tube that the in coming water is going to goes almost all the way to the bottom. Some like theirs to be above, some don't. Above causes splashing and noise unless a sock or splash basket/tray are employed.

1" is fine, leave it alone. Like said, adjust the out flow valve until you find the sweet spot.