Herbie drain plan - use the largest drain possible?

[Zero_Cool]

Tank is reef ready with center overflow box. Has 4 holes in bottom - 2x 1.5 inch drain bulkheads and 2x .75 inch return bulkheads. I plan to run a Herbie style drain setup. Intended flow through the drain/sump is a max of 800 gph.

Question: with that intended flow rate, do I:
- Use 1.5 inch plumbing for both drains - or
- Reduce the main drain to 1 inch and leave the secondary drain at 1.5 inch - or
- Reduce both drains to 1 inch

Basically just want this to be as silent as possible and have previously run the louder Durso mods.

 

[FSP]

I would do both 1.5" durso drains. It will do close to your number silently.

I don't love Herbie, but if you were to do one, 800 gph @ 1.5" plumbing, it would be a hassle to purge the air. Reduce the siphon to 1", but the open channel/dry emergency cannot be oversized. Stay at 1.5".

 

[Zero_Cool]

Thank you.

I believe I read that a gravity drain 1.5 inch can handle 1400 gph which is nearly double what I want my standard flow to be (a full siphon 1 inch drain can pull 1100 - 1400 gph but will be controlled by my return pump dialed back to supply only 800 to the tank).

That is very interesting regarding the potential difficulty generating a siphon in 1.5 in pipe. I had not thought of that.

Please check my thought process here:

Return pump supplies 800 gph to the tank

Use 1.5 inch bulkheads for both drains

Leave emergency drain 1.5 inch

Main drain reduced at bulkhead wet side to 1 inch pipe

Continue 1 inch main drain on bulkhead dry side to sump through gate valve

Expand 1 inch main drain to 1.5 inch drain fitting in sump (sump is an Ice Cap 36xl with 2x 1.5 inch drain fittings)

Will this work or will there be an issue with the reduction at the 1.5 inch bulkhead?

 

[FSP]

Sounds okay if you're good with a Herbie setup. The 1.5" bulkhead at the sump might be a concern for the siphon, but there are easy enough workarounds if it turns out to be a problem.

I believe I read that a gravity drain 1.5 inch can handle 1400 gph

Open channels/Durso drains can handle a lot of flow, but the kicker is how much they can handle silently. Above a few hundred gph @ 1.5", they are not silent and produce more bubbles.

 

[Zero_Cool]

Open channels/Durso drains can handle a lot of flow, but the kicker is how much they can handle silently. Above a few hundred gph @ 1.5", they are not silent and produce more bubbles.

That was my experience previously. Was easily pushing double through the overflow (all 4 holes used for durso pipes with returns plumbed over the back). Results were noisy, splashy with tons of bubles and salt creep everywhere.

I am hoping this time around to reduce all of that with less flow through the sump and for flow internal to the DT.

 

[t5Nitro]

Sounds okay if you're good with a Herbie setup. The 1.5" bulkhead at the sump might be a concern for the siphon, but there are easy enough workarounds if it turns out to be a problem.

Open channels/Durso drains can handle a lot of flow, but the kicker is how much they can handle silently. Above a few hundred gph @ 1.5", they are not silent and produce more bubbles.

Found this thread and not to derail more than this one question to avoid a new thread --

The comment about the 1.5 inch drains at the sump:

I've got three 1 inch drains leaving the tank and have three 1.5 inch entry bulkheads to the sump. Should I upside the drains immediately after the overflow box on the tank side or right at entering the sump bulkheads? Drain design is herbie.

 

[Zero_Cool]

Excellent questions. The concern posted I beleive was will 1.5 inch into the sump cause issues starting/keeping a siphon.

You mentioned that you are currently running Herbie. Have you experienced any issues with the siphon on your main drain?

 

[t5Nitro]

My tank isn't set up yet. Interested to hear peoples suggestions and thoughts.

 

[Zero_Cool]

Got it. Mine isn't set up yet either. I hope we get an answer to your questions.

 

[FSP]

Depends how much water you plan to move; what gph? A 1.5" bulkhead at the sump will very likely not bother anything (just mentioned it as a possibility) if you want to run full 1" plumbing, but bigger is not better when it comes to the siphon line.

 

[Zero_Cool]

Thank you FSP.

For my plan at 800 gph I will reduce to 1 inch at the bulkhead and reconfigure the sump drain attachment to support a the 1 inch pipe in an effort to make the siphon as stable as possible.

 

[FSP]

Sounds good. I mentioned some workarounds earlier if the siphon doesn't want to purge air due to too using pipe too big, horizontal runs in plumbing, bad spacing between lines in the overflow box, etc.

First is drilling a small hole or two just above where the pipe enters the water level of the sump. This allows air to escape and doesn't otherwise interfere with the siphon.

Another is placing the gate valve as close to the sump as possible vs putting it closer to the overflow box. In normal operation (properly designed siphon drain with sump under the stand), it's not important, but with long drops like basement sumps or other common issues, it can matter.

Last I can remember is lowering the siphon to increase pressure on the line. The siphon line in the overflow box usually doesn't have to be more than a few inches below the surface of the water to prevent a vortex, especially with a U bend or elbows, but lowering the standpipe or removing it altogether can allow enough pressure IF your sump is capable of accepting the extra water.

 

[Zero_Cool]

This is great. Thank you.

 

[FSP]

Happy to help.

Last I can remember

Another thing is keep the siphon line an inch or less under the water level in the sump. It can technically be above, and that would solve a lot of issues on its own, but it would be noisy.