Pvc Overflow Issues

[Kilchisblue]

Let me start by saying that I understand this has probably been answered before. I have been reading and tinkering with this bloody thing for a week now.... If you have a good link please put it up.

Ok, I made a PVC overflow similar to kingdiy on Youtube. The main differences are:
1. Threaded 3/4 inch PVC instead of slip/glue. All connections have thread tape and do not appear to leak.lea.
2. I have not, yet, hooked up a check valve. Thus, to prime it at the start I dunked it and shook/tilted the air out.
3. The vent tube, tallest pipe, is fully capped off. It does not vent. I did this because with it vented the flow stopped and began to flood the tank. I have a spare cap with a hole drilled in it but after trial and error lastnight I stuck with the sealed cap because it worked.

My problem is that it will not restart if I test a "power outage"

As for modifications, I have a new elbow piece that I have siliconed a hose barb into. I can simply unscrew the old, replace with new, connect check valve and by on my merry way. This will be done tomorrow after the silicone cures.
Additionally I'm thinking of getting an aqualifter to put in place of a check valve.

The outside tube sits aprox 1/2 inch higher than the inside tube. Its because of how far some pieces are threaded as opposed to others.

Can anybody shed some light on what I am doing wrong or why it only seems to work with the vent sealed?

Pictures.... I will put some up. I can't right now figure out how.

Cheers!

 

[Kilchisblue]

 

[Kilchisblue]

I thought that my return line might be too small. Today is my grand rebuild, add check valve, vent top tube, replace return hose with larger hose.
Ill post my results, crossing my fingers.

Also I had a crazy idea, would it work to connect my return to a T that attached to the check valve, use suction of water falling through return to draw out air constantly?

 

[bigdreams]

My suggestion is setting up a proper Herbie style overflow, with two drain lines, one at full siphon through other as emergency drain line. Sump will be silent this way. Yes it means either drilling tank or getting an overflow box (I recommend eshopps 1100). king of DIY's DIY project is a nice project but I wouldn't risk ruining my hardwood floors from a clogged drain. Yes it happens. Maybe if tank were in basement I would try it. This is one area I wouldn't mess around with. Oh yeah, make sure you have a GFCI outlet or adapter to keep you safe. If you really want to DIY, then make the overflow box yourself.

Herbie Overflow Plumbing Guide for Quiet Reef Aquariums - gmacreef


Good luck and stay dry!

 

[Kilchisblue]

Check valve added, I've increased return line size. Still sucks air when I do a power outage test. Seriously hitting a wall here.

ANY IDEAS?

 

[Kilchisblue]

Thanks for the reply!
I think I'm going to buy an aqualifter after all this riff raff.

I just can't figure out why this overflow doesn't seem to work as it is supposed to. Apparently some people use them without issues.

If I have to take my tank down at any point I will definitely be drilling it!

 

[Kilchisblue]

Oh for anybody else I figured out you can run a long air line from the check valve and start a siphon on it. It will continuously purge air bubbles but if the power goes it will lose siphon. So it can maintain a strong siphon but not start it.

 

[Kilchisblue]

here is the latest. No leaks. No air in tube unless power goes out. I am truly stumped why it will not restart on its own....

 

[mossman]

See post below. I think you may have one of these issues.

 

[mossman]

Is this the video you followed?

I noticed the drain hose you have connected to the PVC is a little restrictive. Try using a section of pipe the same size as the drain and converting over to larger tubing a few inches below the bottom of the tank.

Also, is that a check valve on the tall pipe? I think that hole needs to be open to allow air to purge during priming, and to prevent a vacuum when the water is draining. In other words, remove the check valve if that is what it is.

Lastly, make absolutely sure all your fittings are air tight (did you use primer and glue?)

Here's another video with an explanation of how it works:

 

[mossman]

Post edited. See below response.

 

[mossman]

I just read your original post again, and it answered a couple of my questions (sorry). I'm pretty sure the standpipe needs to be vented. I'm not sure why venting it caused your tank to overflow. Have you tried drilling a small hole in it as opposed to leaving it open? The only other two things I can think of is it seems the outside U part of the drain needs to be at the same level or lower than the inside, or else you'll lose siphon (the " how it works" video should shed some light on this), and the smaller tubing connected to the outlet may be too restrictive. Try removing it temporarily.

In summary, my suggestions are:

1) Drill a small hole in the standpipe cap for venting
2) TrI'm pipe on inside U connection so inside/outside are at the same level
3) Increase size of outlet hose.
4) Triple check that everything is air tight, and ensure the check valve isn't leaking.

 

[mossman]

On second thought, I don't think it matters if the U portions are the same height. The outside U and outlet location will dictate the water level of the inside U when power is off. I don't think that's the issue. The fact that it only works if the standpipe is closed off tells me air is somehow making it's way back up to the top U and breaking the siphon when you turn your pump off. I would suspect either a leaky fitting or leaky check valve.

Just thinking out loud here, but I'm wondering if having the smaller hose connected to the outlet causes turbulence when the water flow stops and a gulp of air is making it's way back to the top U and breaking the siphon. Make sure the tube is adequately submerged in your sump and this shouldn't be an issue.

 

[mossman]

Can anybody shed some light on what I am doing wrong or why it only seems to work with the vent sealed?

To clarify, you mean it only drains properly with the vent sealed, but regardless, it will not restart after a power outage, correct?