Help with fine-tuning DIY hob overflow

[KonradTO]

Hi everyone,
For my new build I decided to make things more difficult and go the DIY way. I made an hob overflow starting out from an aquaclear 70 hob filter.

Now. I had a problem with this configuration because of gurgling noise. So I decided to remove the elbow, close the ball valve in the drain a bit and run the water level higher than the pvc overflow pipe. The problem I have now is that the water level in the return section of the sump fluctuates, as well as the level in the hob overflow, as if some kind of turbolence is increasing and decreasing the amount of water that can go down the overflow drain. Ideally I would like to open the valve all the way so all the water that goes up with the return pump will go down the overflow, but with that setting a lot of air get trapped in the pipes and makes that horrible gurgling noise. Any suggestions?

 

[Formulator]

The fluctuating water level is a toilet flush effect and means you are repeatedly starting/breaking siphon. For quiet operation you could really use a second drain. Then you could set up a herbie style overflow. For now you could try to balance the siphon better by closing off the gate valve a bit more, but you may not have quite enough height in the overflow for that.

 

[00W]

I'm assuming because they're are no pictures of inside the tank that you have no internal box within the tank.
An internal box will give you a constant water level due to water going over the weir evenly, no splashing from anything and no turbulence within the tube.
All of this will add air and in effect give you the flushing action.
Not using a genuine U-tube is also much harder purging the air from. It can't go up and over so you'll really have to get all the air out of the tube.
As far as noise take off the elbow and replace it with a T.
Cap the top of the T but drill a small hole in it, as a safety and also as a burp.
It won't remove all the noise but it'll quiet it down a lot.

 

[KonradTO]

The fluctuating water level is a toilet flush effect and means you are repeatedly starting/breaking siphon. For quiet operation you could really use a second drain. Then you could set up a herbie style overflow. For now you could try to balance the siphon better by closing off the gate valve a bit more, but you may not have quite enough height in the overflow for that.

Yeah I was thinking to drill a second drain, but I will wait to find another cheap secondhand aquaclear for that, because drilling this one was already a challenge. The plastic is quite brittle and I almost chipped the whole bottom when drilling. I will get a spare and try to fit 2 holes. I could also go with the aquaclear 110 in case. For now I did what you suggested, the gate valve is closed enough to keep the gurgling noise at minimum but the level seems constant.
Incredible you learn everyday something, I did not know about this toilet flush thing..in my old tank I had a setting similar to that of king of DIY, but with the U pipe that collects water from the tank placed inside a filter section of an AIO, so turbolence was not a problem I guess.

 

[KonradTO]

I'm assuming because they're are no pictures of inside the tank that you have no internal box within the tank.
An internal box will give you a constant water level due to water going over the weir evenly, no splashing from anything and no turbulence within the tube.
All of this will add air and in effect give you the flushing action.
Not using a genuine U-tube is also much harder purging the air from. It can't go up and over so you'll really have to get all the air out of the tube.
As far as noise take off the elbow and replace it with a T.
Cap the top of the T but drill a small hole in it, as a safety and also as a burp.
It won't remove all the noise but it'll quiet it down a lot.

Yes you are correct indeed, I have no surface skimming weir for now. I am building something for this purpose but I was hesitant to place it in the tank because it occupies space and the tank it is already small (18g).
Regarding the squared pipe Vs the U pipe, honestly I am not having huge issues with removing air because the shape of the aquaclear pipes combined with the suction of the siphon makes all the air accumulate in one corner, where they placed this plastic pin thing. I placed a second U pipe to increase the flow to the sump and added a check valve right there. From time to time I remove the air that accumulates in there, but as you say if I had the surface skimmer I would not have this problem.

I made the Weir box with acrylic

And this is the front look

I don't know why no one did this before, aside from small challenges with noise the system is very functional. From time to time I activate the filter pump for few seconds on a timer, and all the bubbles go away from the U pipe. Also in case of siphon being lost the pump will restart it in one minute

 

[00W]

Yes you are correct indeed, I have no surface skimming weir for now. I am building something for this purpose but I was hesitant to place it in the tank because it occupies space and the tank it is already small (18g).
Regarding the squared pipe Vs the U pipe, honestly I am not having huge issues with removing air because the shape of the aquaclear pipes combined with the suction of the siphon makes all the air accumulate in one corner, where they placed this plastic pin thing. I placed a second U pipe to increase the flow to the sump and added a check valve right there. From time to time I remove the air that accumulates in there, but as you say if I had the surface skimmer I would not have this problem.

I made the Weir box with acrylic

And this is the front look

I don't know why no one did this before, aside from small challenges with noise the system is very functional. From time to time I activate the filter pump for few seconds on a timer, and all the bubbles go away from the U pipe. Also in case of siphon being lost the pump will restart it in one minute

Cool Cool
Just be careful hate to see a flood.
Eshopps makes a great nano box for about $80.
More power to you for the DIY
Try what I said to quiet the noise.

 

[KonradTO]

Cool Cool
Just be careful hate to see a flood.
Eshopps makes a great nano box for about $80.
More power to you for the DIY
Try what I said to quiet the noise.

Flood is not in the equation hopefully. I have an optic sensor that shut the return pump off in case the level in the DT goes over the limit. We'll see, I am a DIY person so I would rather fail with DIY than buy

 

[00W]

Flood is not in the equation hopefully. I have an optic sensor that shut the return pump off in case the level in the DT goes over the limit. We'll see, I am a DIY person so I would rather fail with DIY than buy

Nice!
That's high tech!
Keep me updated and shoot over some pictures of the tank!
I've always been a "cheap " reefer and love used/DIY so right on, good for you!
Joel

 

[KonradTO]

Ok I though I solved the noise issue but the system is too unstable and the minimum change in the valves make everything go nuts again. Yesterday I increased a bit the flow in the fuge section, so basically I just changed where the water goes in the sump without changing the flow through the main drain valve, and this caused the water level to start fluctuating again. I am gonna try the T pvc thing today. Would this work as well by drilling the top of a the elbow? Well I probably am gonna find out

 

[KonradTO]

Just wanted to give an update in case someone else will encounter this same issue. Being in the situation where for now I can only go with one single drain, I could not add a second emergency drain and run the level of the water high enough to avoid noise. As suggested by 00W I opted for a single durso with no air valve, just a bit of air tubing going through the hole in the cap. I have ball valve instead of a gate valve, and that makes everything more difficult. In the end I solved the noise with the durso and the fluctuations by getting the flow right in the spot where it must be (almost 5h of playing with the valve). Something I realised too late is that when you make any changes with the valve, it is necessary to wait at least 30-60 minutes before checking again.
Will post pics soon