Need solution to Power Outage / Return Draining problem

[rallendorph]

Hi Folks,

I realized that I have a potential disaster waiting to happen in my new tank setup. The issue is that my return bulkheads are ~ 2" below water level, and I have ~6" of Lockline pipe connected to them internal to the tank. The end (output) for the Lockline pipe is ~4" to 5" below water line.

So here is the issue, On a power outage, both pumps stop, and the returns will act as a siphon, and drain an additional 4" to 5" of water from the tank to sump. Add another 1"+ to this from overflow volume. Currently, 50G water will overflow my sump and cause a flood.

I don't want to set my sump up with 50G of empty space to accommodate the total overflow, and my pumps have issues restarting if there is air in the return line.

The two potential solutions I am considering is a 1" check valve, and, or a 1" PVC solenoid on each return line. I am hesitant to rely on the check valve since any leaking will eventually result in flood, and the PVC solenoids are $$$. However, the PVC solenoids would maintain suction in the return pipes, so the pumps should start up without issue.

I'm sure many of you have returns that do not go over the back of your tank (I.E always under water level). How have you addressed this ?

If you used a Check valve where did you put it ? towards top of water path (upstream of pump), or near sump (behind pump) ?

I include a pic of general system layout. I appreciate any thoughts, experiences you have.

Thanks,
Rob A. :beer:

[DerekW]

If your return lines go through the wall of the overflow box as it appears in the picture, you could drill a hole approx 1/4" in the return pipe that is inside the overflow box, and it will break the siphon as soon as the water drains from inside the overflow.
Water will squirt out of it, but if you want you could put an airline check-valve in it so that it will only suck water in, might start a venturi though. Just make sure to clean th holes regularly
Does that make sense?

You could also try something like this ideahttp://www.krob.com/aquarium/siphon.htm

[rallendorph]

dick182 -

Hi, thank you for your reply.

Yes, the return goes through the overflow wall. I am using Durso style stand pipes for the Main Drains. So, the only portion of the Return pipe that is ever out of the water is the 90Deg Elbow that routes the return pipe through the overflow wall. I throught about drilling a hole through the elbow, but am very concerned that if the hole is too large, then I have a significant stream of water shooting through it. And, if the hole is too small, or becomes smaller due to CA (or other) buildup then I have a very effective venturi. One thought I had was to drill a larger ~1/2" whole through the elbow, and then glue a tube into hole. So that I could feed the tube through one of the crenalations in the overflow. If the tube was above water level, that should be large enough to break the siphon,and would take quite a bit of build-up to plug it up. Or, maybe there is some type of Elbow that contains a drain I could use.

I don't trust Check valves. If / when they work life is good. If they stick (at all) then you have a potential disaster. Otherwise the solution in the thread you supplied seems reasonable.

Do any of you use Check Valves ? If so, have they ever failed ?

Thanks again,
Rob A. :beer:

[o2manyfish]

I use check valves----

Several issues with them:
1) They are not reliable; Coraline, sand, detritus will all cause them to not seat.

2) No matter the type: Flap, ball, spring - after in use for awhile they have a tendency to stick in the open position

3) When they do close, because of just all the things that happen in an aquarium they will not sit 100% tight and will continue to trickle water.

Check valves are not a safe or reliable solution in my opinion. Given that you have 2 pumps, I would recommend setting up a closed loops for the lower tank returns, and then adjusting your locline for the top returns closer to the surface.

It's not imperative that all your flow runs through to the sumps/fuges - So be safe and replumb to that the water stays flowing :)

Dave B

[Nagel]

In my experience, check valves work EVERYtime you test them, but when you NEED them, they fail. I work for a LFS that maintains quite a few tanks in NYC, and during the big blackout in august, EVERY SINGLE checkvalve failed, flooding over 2000g total in several office buildings...

The electronic solenoid / valve is more failsafe, I would go that route... But you could also drill the siphon break and then route a piece of airling to just below the water surface. No venturi, and as the water level lowers, siphon will break. I have my drains just mounted as standpipes in the tank, no overflow boxes. So, when the pumps are on, the water will rise 1" or so above the level when the pumps are off. It's this 1" that you want to route the siphon break tubing too. As long as the pumps are running, never a chance for venturi (only gonna be taking water from your display anyway), and when the power goes out and it drops 1/2 inch, siphon will break...

HTH

[eljefe3]

I too have a couple of 1-way valves and one of them already has a leak. The power went off the other day and my water drained into my sump just like it's supposed to. However I noticed that the sump started overflowing so I turned off the ball valve at one of the pumps. This stopped it, but keeping it off isn't a good solution. The pump and the valve sit at a level below the top of the sump and the water drained from the tank down through the pump, up into the sump then out into the stand.

What would the best solution for this be assuming that my generator won't start ( even though it should as I have an automatic transfer switch on the generator that kicks on after 5 seconds of no power)?

[rallendorph]

o2manyfish, Nagel -

Hi. Thanks for replying.

Your comments on Check valves echo my thoughts.

Currently I am running an in-line / Closed loop pump. In the Pic it is the three lower Pipes in/out of the overflow. I have a Velocity T4 driving it. I can certainly add lockline segments to each of the overflows so that they crest above the water. In theory this will work. I guess I'll just need to make sure they don't sink, or get pushed down, over time.

Nagel, I'm looking into the PVC solenoids, I expect that I am going to combine an air break of some sort with the solenoid. A bit pricy, but rather be safe than hope a snail doesn't bugger me.

Rob A. :beer:

[rallendorph]

eljefe3 -

Yep, exact scenario I'm working on resolving. Per folks suggestions, I am going to create an above water hump / crest in the return lockline (maybe drill a hole in it as well). I think I am going to rely on a PVC solenoid for each return pipe. As I've indicated a bit pricy, but I'm hoping a resolution to the problem.

Good luck.

Rob A. :beer:

[o2manyfish]

The only issue with the solenoid is you need an always on solenoid so that it closes when the power goes off.

If your running a reef you run the same issue of calcium and crap lodging in the gate and pinning it open.

Calcium deposits are amazing - Everycouple of months my main pump starts to grind, and I open it up to clean all the calcium that has grown on a constantly spinning impeller in the highest flow location.....

Dave B

[Playfair]

Another problem with the solenoid is that it will only shut off (if it works) when the power goes out, but there are a few reasons the return pump can stop. Also, what happens if the solenoid fails?

This isn't really a siphon problem as much as a back flow issue, as there's nothing you can do to 'break' it if all of the plumbing is below the water line.

This happened on our 560gal, and we ended up having to cut our the returns so they could be re-run above the water line with a small drain line allowing air into the system to break the siphon.

There's some pics of this setup on the last page of the "project scrapbook" pictures in our gallery:
http://www.upstatereef.com/gallery/

[DerekW]

Originally posted by rallendorph
eljefe3 -

Yep, exact scenario I'm working on resolving. Per folks suggestions, I am going to create an above water hump / crest in the return lockline (maybe drill a hole in it as well). I think I am going to rely on a PVC solenoid for each return pipe. As I've indicated a bit pricy, but I'm hoping a resolution to the problem.

Good luck.

Rob A. :beer:

Even if the locline "humps" above the water line, it will not stop a siphon from forming. Think of over tank overflows (Like CPR, Lifereef, etc) that is how they work. I'm telling you, the hole in the return line will work, drill a hole that will fit airline tubing fittings and run the end to the bottom of the overflow, or into the tank like you said. Even as far as a stream in the overflow goes, drill the hole on a downward angle and it won't matter, you're not going to get alot of water from a 1/8 or 1/4" hole, I have 1 in each of my returns.

[epon]

afaik no-one has suggested a Y locline fitting on the top most left and right returns. You could use one of the Y ends to reroute another locline section up and pointed back down just under the water surface. Soon as the water reached the opening seems like that would be all you need to break siphon. HTH

[rallendorph]

epon - Hi. Yes, it's a reasonable idea.

I know that when I started my main return pump (Mak 5 /PCX 100) I had the locline pointing to the side of the tank , and the pressure of the water hitting the side of the tank 2' away was enough to lift the bulkhead cover off the tank, and create a small mess. :eek: :hammer:

So, this may, or may not be workable depending on setup. But I'll think about how I can set it up.

dick182 - I appreciate your comments, and I think I agree with you. I'm going to figure out if epon's suggestion is viable for me since it's painless to implement, and if not, take your suggestion.

Thank you all for your comments.

Rob A. :beer:

[z28pwr]

What I will be doing and have done in the past is drill a hole in the return PVC facing down that way the water will go to the bottom out of the hole and not toward the top like this
_
|
|\ <-- Hole being drilled from the bottom up so that the water will shoot down instead of up or to the sides.


You will need to clean out the hole once every 3-6 months depending on how big of a hole you made and how fast you grow algae.