Megaflow Overflow problems

Beaun · Jan 22, 2009

It is a Mag Drive 9.5 pump. Documentation says it does roughly 800gph at 4-5 feet. I'v read the overflow gets 600gph. I'll try the ball valve at 4 p.m. EST and let you know how it worked.

EDIT:
I also found this FAQ on the durso standpipe website. It's my issue exactly:

Q1. Flushing Effect - Water level goes up and down!
Answer:

A commonly reported problem when first installing standpipes is what I call a flushing effect. The water level in the chamber bounces up and down at a slow steady cyclic pattern. This is different than the issue above where the water level stays to low. This issues typically is not caused by the size of the air-hole in the end cap. The flushing effect is almost always caused by back pressure in the drain line. Typically the back pressure has two main causes:

1. Drain pipes in the sump being submerged below the water surface to far. Ideally you just want the drain pipes submerged about an inch or two. Just enough to reduce the splashing noise in the sump.
2. Any loops or dips in the drain lines if using flexible tubing. If using hard PVC pipe for the drain lines make sure they always have a slope to them, don't make them perfectly horizontal or perfectly vertical.

The flushing effect works like this: Back pressure in the standpipe prevents air in the pipe from exiting the drain line. Instead of exiting the drain line, the air bubbles try to rise in the pipe slowing the rate at which the pipes drain. The water level in the chamber then rises. The increase in the chamber water level adds pressure to help clear the air from the pipe. Once enough water pressure exists in the chamber to overcome the back pressure, the air is literally is "burped" out of the drain line which crates a sudden rush of water. This is displayed as a rapid drop in the overflow chamber water level. This cycle then repeats itself over and over as the back pressure builds and gets purged.
Click to expand...

I'll have to try these 2 things and see what happens. I do have hose in the already mentioned horizontal "S" which would bring me my back pressure. What I might do is to simply use 1" tubing and ditch the "pool" hose that came with the sump (eshopps reef sump). This way I can get it to be a gradual slope and also have it enter the water directly, vs. having a 3-4" gap between the top of the sump to the water (causing my volume issue).

Otty · Jan 22, 2009

Another real quick way to see if it's the air hole is just take the top cap off and let it have all the air it wants. If it doesn't fix it then search the drain line. Real quick and easy.

Beaun · Jan 23, 2009

Well I went home last night and turned the system on...no problem? I put my finger on the hole and it started doing it again, but after a few minutes it seemed to work itself out. I did mess with the plumbing a bit and that might have been the problem. Air might have been caught in the piping and causing the flush to happen. Now all I have to do is get an elbow to fit on the sump MTP (eshopps reef sump) to get the water in the sump with less noise. I believe its an 1 1/2', but Im not certain.

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Megaflow Overflow problems

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