Overflow Gurgling

[Robert_Popa_918]

Hello! After running a small 20 gallon long reef aquarium with a hob filter for the last couple years, I decided to give a larger tank with a sump a try. I’ve set up a 50 gallon breeder, drilled 4 holes into it, and done all of the work to it. Now that the tank is near completion and I have begun filing and cycling it, I’ve noticed some serious flaws in my design. First I didn’t use any types of overflow designs such as the Herbie or durso. I just have 2 1 inch bulkheads into the side of the aquarium along with a narrow overflow box to cover them. I now have extremely loud gurgling noises coming from the aquarium to deal with. My return pump has to run at the lowest possible setting just to keep the gurgling from being loud enough to cause me headaches. Since this tank is in my bedroom, it makes it difficult to sleep. I would appreciate any advice on how to fix this. I really hope that I don’t have to take apart my current plumbing system. Thank you.

 

[Tonycass12]

You need a gate valve on your primary drain so you can reduce the flow and operate that drain at full siphon. The way they are plummed to the overflow box is going to make this difficult you usually want your secondary drain higher then your primary so it's taking little to no water into it. Maybe you could just replace the overflow box so you can add a 90 to one of the bulkheads and make that your secondary drain.

 

[ca1ore]

If you have enough access to the bulkheads inside the overflow box it should be easy enough to rejig as a herbie.

 

[Dburr1014]

Yup, one elbow facing up and one(or none) facing down, or as much as possible.
Up is your secondary, with small trickle. Lower is primary with gate at the sump.

 

[mjw011689]

Ditto what everyone else said. If you can get a 90 elbow on one of them to point up, that will be your secondary or emergency drain. The other will be your primary and you will need to put a gate valve somewhere in line (probably near the sump where it’s easier to access).

start with your return pump on the higher setting and start closing your gate a little at a time, giving a few min between adjustments for it to settle. Once all the air comes out it will be a full siphon and be silent. You’ll need to keep adjusting the gate and return pump to get to that sweet spot where your main drain with the gate goes full siphon and to where the water returning isn’t QUITE fast enough to fill into the emergency/secondary drain. My herbie runs silent. Water level in the overflow sits RIGHT below the secondary drain. Only time it changes is when my water evaporates a bit and the level in my return section drops a tad. Once I top off; it goes back silent. ATO will solve that.

 

[bradreef]

You could also plumb with a t and airline like this

 

[Bret]

Your issue is both drains are trying to act as siphons, but can't due to not enough flow from the return pump (do not try to increase flow with your current setup, it is fairly dangerous right now as implemented), causing them to suck in air, which creates the gurgling noise.
The solution as others have already mentioned is to convert this to a Herbie system.
the easiest way, if you have enough room is as follows:
1: Add elbows on the tank side of both bulkheads, one facing up, one facing down
2: Add a standpipe to the upward facing elbow. The height of the standpipe should be about an inch below the overflow teeth
3: Add a gate valve to the drain line with the downward facing elbow (should also add a ball valve to the other drain)
4: Set your return pump to your desired flow rate
5: Tune (adjust the gate valve) until you have full siphon in the main drain, and the water level in the overflow box is just below the standpipe of the secondary drain.

This should get you a nice quiet and safe overflow setup.
If you cant fit the elbows in the overflow box, your next best option would be to convert both drains to Durso style with an external tee fitting drilled for air vents. Let me know if you need a description on how to do this (it was shown in an above post by bradreef).

 

[IPT]

I wanted a super narrow overlfow in my 50 so made the interior box like youre. No bulkheads though, Just holes. Then I made an exterior box with the bulkheads on the bottom. One taller PVC and one lower so I could use the gate valve and adjust the flow.

Obviously if you can get an elbow IN the current box that would be the easiest fix. If it's too narrow (like mine is) building and exterior box will solve the issue, though it will of course require more materials and work.