Herbie/siphon with a HOB overflow

[paul_111]

Hi All;

As I have read, the Herbie method uses a valve after the drain to keep the water level above the drain intake, thus inducing a siphon. The second drain is full open at a higher water level for an emergency and is kept dry.

I have an eshopps 1800 HOB overflow, which claims 1600 gph through two 1.5" drains. The return pump is a dart through an OM 4-way.

I don't think I'm getting nearly enough flow out of the overflow.

If I close down the valve to eliminate air, the flow out of the box is way too low. If I open the valve all the way, I get much more flow, but bubbles as well. Even full open I don't think it's enough flow.

I have lowered the intake box so the teeth are just barely above the surface of the water in the DT.

Why doesn't the siphon flow more than the open drain with air?

What am I missing?

Thanks,
Paul

[uncleof6]

The bottle neck is the internal box, and the piping to the external box. (The 1.5" full siphon in the external will flow ~3000 gph without breaking a sweat, depending on the length of the drop) Also the size of the internal box is too small for the flow rate capability of the 1.5" full siphon. You have a high performance exhaust with a low performance intake. The result is poor performance. Incidentally, a 1.5" air/water "open" drain, will not handle 400 gph without issues, so if you are doing better than that, you are a little ahead. You need a high performance internal overflow (or internal/external) to compliment the dart and your full siphon drain. DIY here, this involves modifying the tank.



Jim

[paul_111]

Jim;

Thanks for the info. So how do they make the claim of 1600gph through that box? Is it plain 'ol advertising magic? ;O)

Do you have any suggestions of how I can increase the flow without drilling the tank? I don't feel comfortable dropping the level a bit and drilling while stocked. I wish the tank was drilled...

Thanks,
Paul

[uncleof6]

Originally Posted by paul_111

Jim;

Thanks for the info. So how do they make the claim of 1600gph through that box? Is it plain 'ol advertising magic? ;O)

Do you have any suggestions of how I can increase the flow without drilling the tank? I don't feel comfortable dropping the level a bit and drilling while stocked. I wish the tank was drilled...

Thanks,
Paul

Well on the low end, 1600 gph requires 24" of linear length (without teeth) for the overflow (the internal part.) The dart, wide open @ 4' of head, = 3000 gph. The 4-way is knocking the flow down a bit more. So out of the gate, you have a bit of a mismatch going on. I can't sit here and tell you that the HOB will not flow 1600 gph, but I know what a 1.5" full siphon standpipe will flow. So the bottle neck is the HOB.

I don't recommend anyone modify a tank (drilling holes) that is running. You need more internal length, and more up over the back, which will probably equate to more external length as well. Of course you could always take the "easy way out" and throttle the dart till it all balanced out.

Jim

[golf nut]

You should really use the Dart on a closed loop with the 4 way, no need to drill, use the HOB to feed the sump only.

[jacksonpt]

I'm by no means a flow/plumbing expert, so take this all for what it's worth... I'm simply speaking from my experience.

Originally Posted by paul_111

As I have read, the Herbie method uses a valve after the drain to keep the water level above the drain intake, thus inducing a siphon. The second drain is full open at a higher water level for an emergency and is kept dry.

While I understand how the herbie method works in theory, I think in practice it's is exceptionally hard to get a single drain at full siphon matched to your return.

Originally Posted by paul_111

I have an eshopps 1800 HOB overflow, which claims 1600 gph through two 1.5" drains. The return pump is a dart through an OM 4-way.

I don't think I'm getting nearly enough flow out of the overflow.

I have the PF1000 box from Eshopps, 900-1000 gph and I believe it can handle that flow when setup properly. Mine is handling slightly less than that, probably in the 750gph range. I've got 1 drain running at full siphon (dialed back with a ball valve) and the other using a fairly standard standpipe.

Originally Posted by paul_111

If I close down the valve to eliminate air, the flow out of the box is way too low. If I open the valve all the way, I get much more flow, but bubbles as well. Even full open I don't think it's enough flow.

I have lowered the intake box so the teeth are just barely above the surface of the water in the DT.

Why doesn't the siphon flow more than the open drain with air?

Are you talking about the siphon from the internal box to the external box, or from the external box to your sump?

Something to keep in mind... the water level in your external box will have a noticeable effect on how the flow from the internal box to the external box. Compare the water level in your tank to the level in your external box. The closer they are, the slower your flow will be.

[paul_111]

Originally Posted by golf nut

You should really use the Dart on a closed loop with the 4 way, no need to drill, use the HOB to feed the sump only.

Golfnut;

How would you do that without drilling? Do you have any pictures?

Thanks,
Paul

[paul_111]

Originally Posted by jacksonpt

I'm by no means a flow/plumbing expert, so take this all for what it's worth... I'm simply speaking from my experience.

I have the PF1000 box from Eshopps, 900-1000 gph and I believe it can handle that flow when setup properly. Mine is handling slightly less than that, probably in the 750gph range. I've got 1 drain running at full siphon (dialed back with a ball valve) and the other using a fairly standard standpipe.

Jackson;

Can you please expand upon "when setup properly"?

Thanks,
Paul

[jacksonpt]

Originally Posted by paul_111

Jackson;

Can you please expand upon "when setup properly"?

Thanks,
Paul

From my experience, the biggest thing is keeping the water level in the external box low, which unfortunately makes the overflow louder.

[golf nut]

Originally Posted by jacksonpt

I'm by no means a flow/plumbing expert, so take this all for what it's worth... I'm simply speaking from my experience.


While I understand how the herbie method works in theory, I think in practice it's is exceptionally hard to get a single drain at full siphon matched to your return.

Experience is good, I agree it is virtually impossible to match the return pump.

I recently had an incident where the overflow was quiet during the day but would get noisy later in the evening, we eventually discovered that the power to the pump became a little higher in off peak hours and worked a little harder, the slight excess flow made a noticeable difference to the noise of the overflow box.

[NanoReefWanabe]

you dont need to drill for a closed loop, you can do it all over the top of the tank...it depends how big your tank is though...cause an over the top dart closed loop with four inlets is going to be very intrusive looking in a tank smaller then 150ish gallons...two 2" inlets and four 1" or so returns...

as for your box flowing at 1800gph, i am sure that is if you have both drains going at noisy a** air entrained durso style...as jim mentioned you can easily pull 3000gph through a 1.5" drain at full siphon

[golf nut]

You don't need two 2 " feeds to the pump, use one 1 1/2 pipe and split it behind the rock into multiple inlets for greater coverage and less velocity, if you get the flow to the tank you likely need only 800 or so through the sump , therefore your HOB problem will go away.thats 5 pipes, four 1' and one 1 1/2, use a piece of trim to hide the pipes, its as intrusive as an overflow half the size of what you have now.

[NanoReefWanabe]

Originally Posted by golf nut

You don't need two 2 " feeds to the pump, use one 1 1/2 pipe and split it behind the rock into multiple inlets for greater coverage and less velocity, if you get the flow to the tank you likely need only 800 or so through the sump , therefore your HOB problem will go away.

dart has a 2" inlet, a single 2" inlet into he tank would suck little fishes into fish paste, 1.5" could (would likely) create cavitation in the pump regardless of how many open ends the pipe had...never, never starve the inlet of a pump....you should likely use 3" pipe and bush it down directly at the pump, however multiple 2" inlets should suffice...obviously your manifold should be large enough to handle the flow from both inlets and not create any negative pressure at the pumps inlet...ideally, 2-2" inlets into a 3" or larger manifold that carries that size to the pump, then bush it back to the 2" inlet of the pump.

[golf nut]

Originally Posted by NanoReefWanabe

dart has a 2" inlet, a single 2" inlet into he tank would suck little fishes into fish paste, 1.5" could (would likely) create cavitation in the pump regardless of how many open ends the pipe had...never, never starve the inlet of a pump....you should likely use 3" pipe and bush it down directly at the pump, however multiple 2" inlets should suffice...obviously your manifold should be large enough to handle the flow from both inlets and not create any negative pressure at the pumps inlet...ideally, 2-2" inlets into a 3" or larger manifold that carries that size to the pump, then bush it back to the 2" inlet of the pump.

The Dart is running on a CL, Reeflo makes a 2" inlet for sump returns and needs to be 2", no head loss on the closed loop means that 1 1/2 is more than sufficient, splitting the outlets on the inside of the tank will as I said get better coverage and reduce the velocity at all ports to just 900 gph.

[uncleof6]

The rule with pumps is do not restrict the pump intake. This includes reducing the inlet pipe diameter to a size smaller than the pump outlet. The word from reeflo, is the Dart will operate, without cavitaiton, with the inlet pipe diameter at 1.5".

There is no static head pressure on a closed loop, but by the time the plumbing turns into the pasta salad that is being recommended here, there will be a bit of friction loss with the fittings (outlet side-- 90's, tees, unions, valves), the om, yahdah yahdah. That all gets added to the static head loss, for the total head loss. Ok so static is O, so you are gaining a 4 - 5' advantage, and adding it back with the pasta salad (ball parked.) Whoopie. Of course, the OP has got a pasta salad sump return going on already.

I really don't think this should be going so far astray, considering the question was concerning the overflow/drain system-- over an opinion concerning the OP's choice of pumps.

Jim