Who has experience with a DIY PVC overflow?

[trilinearmipmap]

Like this kind:

https://www.youtube.com/watch?v=7DFk4bnIxEg

Just wondering who has been running these for a while, and any problems with failure of the overflow / floods etc.

The design looks pretty well foolproof and I was looking at a couple of redundant failsafe systems: float switch to cut the return pump, run tubing to venturi on return pump to keep the overflow primed, and water detector / alarm. Also I would run it as a trial in my basement for a while to test it out.

Interested in real life experiences with these. I have a 30 g cube up and running, I am not going to drill it.

[Reef Pilot]

I used one for a while with my refugium. It was indeed foolproof (although many are not). Here is a pic, in post #12.
http://www.canreef.com/vbulletin/showthread.php?t=102101&page=2

[The Guy]

If you don't mind looking at the PVC piping in your Display tank, it looks like it would do the job for you. I've always drilled my tanks and used an internal overflow with a herbie system.

[trilinearmipmap]

Just wondering with the airline to the pump to suck air to prevent losing the syphon, can the airline itself not become a syphon and cause a flood?

[Reef Pilot]

Just wondering with the airline to the pump to suck air to prevent losing the syphon, can the airline itself not become a syphon and cause a flood?
As soon as the flow stops as with a power outage the water level in the tank drops below the overflow immediately, so no more flow from the tank. And the airline syphon will then break, too.

And to be extra safe, you can put another open elbow (instead of the plug) pointed up at the end of the overflow that will then be slightly higher than the serrated overflow pipe, in case the overflow gets plugged with debris.

[newsaltfan]

So I’ve been running this type of overflow for about 12 months now…. First off let me say I’m a Chicken $hit when it comes to gambling with water on my wife’s carpet. Redundancy is my middle name. I run two 1 inch drains on a piddly 20L. I have tested things and a single overflow handles the volume I introduce into the tank.

Nothing is perfect…

Syphon failures….
In the 12 months I have been running the dual overflows I have had the same 1 of the 2 fail twice. The first time it failed I simply restarted it (by removing the air from the inverted “U” that transitions the overflow from the inside of the tank to the outside) and viola back in business. Never attempted to determine why it failed. So after the second failure on the same overflow I wondered what the issue was compared to the other overflow. Well apparently the one overflow was terminating barely above the waterline in my sumps filter sock and as the filter sock clogged the water level would rise and cause back pressure resulting in the loss of syphon. Well at least that’s what I figured. Since determining this was likely the issue I cut an inch off that drain and no issues. The other drain was already shorter.

Now as for the check valve mentioned in the YouTube video… sure it works but remember the C.$. from above I don’t trust a $2 fitting from the LFS especially if you aren’t running 2 overflows for redundancy…. I drilled and tapped holes for ” http://www.lowes.ca/pipe-fittings/watts-pl-3008-14-quick-connect-x-18-mip-90-elbow_8780434.html&linkloc=cataLogProductItemsImage (http://www.lowes.ca/pipe-fittings/watts-pl-3008-14-quick-connect-x-18-mip-90-elbow_8780434.html&linkloc=cataLogProductItemsImage) “ and added “ http://www.lowes.ca/valves/watts-pl-3011-14-pvc-compression-coupling-valve_g1194532.html (http://www.lowes.ca/valves/watts-pl-3011-14-pvc-compression-coupling-valve_g1194532.html) “ this in line. I realize this adds a few dollars to the DIY build but worth the costs in my mind. And these fitting can be reused on other projects if these ever get torn down.

At one point I did try and plumb these, let’s call them bleeder valves, to the intake of my return pump but I could never get enough pull on the ¼ inch rigid water line used with the above fittings. I figure a larger return pump would solve that but I am already running a Mag 7 on a 20 L tank.

Once a month I manually purge any trapped air. Better safe than sorry.

I’m by no means an expert but if you have any questions ask away.