What am I not understanding?

[DaveB]

(Be advised: I'm well aware that the best answer may be "everything.")

My overflow has a 3/4 and 1" bulkhead and I finally got around to setting it up for a sump. I'll probably drill another 1" and run a herbie setup for the noise issues, but for now I was just testing things out.

If I'm understanding correctly, the 1" pipe will handle 600gph of flow. The pump is 950gph at 0 head, and it's on the floor below about 50" of total height covered before the return.

Anyway, I have a gate valve on the intake and have to turn it quite a way to achieve a perfect level. And if I'm seeing things correctly, this gate valve bottlenecks a bit too, as the actual width of the hole in the middle is 3/4". For now it's a straight drop into the sump, no elbows.

The pump gushes pretty hard... actually a lot harder than what my discus are going to like (my experience tells me that the wilds prefer a more tranquil water), which is another issue... so I have a hard time believing that the head is causing so much loss that it's well below 600gph. If that's the case I have to question what my FX5 used to run at (and worse, how low the Eheims are!)

So I'm confused. The math seems to indicate that I'm reduced to below the 600gph coming in, but my eyes disagree. The water is moving. What am I missing here?


Because of the height of the teeth on the overflow and the location of the return (drilled below those instead of going up and over) I am planning to put a check valve in on the return so I can keep the return below the surface and quiet... will that affect the pump's flow? Because of the discus that won't bother me at all... I've just never used one before so I'm not sure.

 

[ruddybop]

My return is also under the water surface.... I did not use a check valve on the return line but after i had my water heidth set the way i liked it... I drill a small 1/8" or 3/16" weep hole about 1/2" above the water line in the pvc so the water would not siphon back through... This wont work with yours from what i understand about yours is that your return is drilled into the glass below the waterline...... ???? A pic would be nice.....

 

[Jc1119]

What kind of pump are you running? @4' head you are probably losing a bit of output. If you're rated for 950 @ 0' you might be losing 200-300 gph at 4'.

Also, your 1" drain will flow at 960 gph if you re at full syphon, such as a Herbie setup. This might explain why you are having to throttle back your gate on your drain(input)

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

 

[ruddybop]

I personally don't like the check valves (only fear is it failing)but I don't see why you can't use one though. I don't believe you will lose any pressure.. either a check valve or you have to do your plumbing like this on your pump input...

 

[DaveB]

There's a few pics in this post. It's stupid. It's entirely possible I'll just plug it when I get my background... if the damn things ever come in (now delayed another 6 weeks. Very annoying!)

http://www.monsterfishkeepers.com/forums/showpost.php?p=4583295&postcount=27

Technically as long as part of an over-the-top return stays above the bottom of the weir that should break siphon. But I seem to recall that being a tad unreliable. A hole would certainly work and let it go deeper too.

John, it's a Mag 9.5. I think I'm going to buy a Mag5 for up here and use the 9.5 downstairs. My discus prefer stiller water (so I don't mind throttling back flow even if a check valve does that) so there's no point wasting electricity to run a 9.5 if a 5 will do. Or I could try to experiment with spray bars or something.

Thanks for pointing out that the numbers change with a full siphon. I thought the other figures were for that, which is what confused me.

 

[ruddybop]

Technically as long as part of an over-the-top return stays above the bottom of the weir that should break siphon. But I seem to recall that being a tad unreliable. A hole would certainly work and let it go deeper too.

Yes if you did an over the top you could go deep into the tank as long as you put a weep hole just above the water line so it doesn't siphon back through..... and plugged your glass hole like you said....

 

[Jc1119]

A mag 9.5 @ 4' head is outputting about 800 gph. 1" drain at full syphon is more which is probably why you're throttled back a bit, but this is supposed to work this way in a full syphon drain. The gate is to adjust the drain so water stays above the drain pipe thus eliminating noise. I would certainly run a backup drain for security though ( Herbie style as you stated earlier)

As far as a check valve goes, I personally like syphon breaks and checks together. I don't think the slight loss of output justifies not using one. They are relatively cheap and just a little bit of added pom..... Siphon breaks can get clogged and checks can fail, but if you run both, you've got a vertually bulletproof setup. Good luck!

 

[DaveB]

The nice thing is that this is going to be almost 100% safe anyway because the stand itself is watertight. It can hold 20 gallons or so before reaching the door level. So even if I screw something up, that should protect me.

I ought to be able to plug the center return hole and go up and over, and set the main intake about an inch below the weir while running a water level about 3/4" above it. That'll be higher than the canopy edge and only about 5 gallons worth would flow into the sump if the power went out, and there'd still be plenty of space for the emergency drain and should be enough wiggle room for it to adjust itself during startup.

My only real concern is if the input and backup both clog... then it'd overflow out the back of the tank... but that's almost impossible.