That water level is about as high as you can make it. It's got to have some fall. As for drilling, maybe just put it into the side holes on that elbow, and see if you can get it quiet moving it back and forth before you start doing permanent mods.
I'm thinking it's the air mixing with water that's making the sound. Usually, the airline tubing will quite it down.
Ok. So what is the purpose of that rubber tubing? I assume there is a certain depth into that standpipe that causes some type of positive result? The hole I was referring to that the water was making noise from is on the output side, not the intake side.
Another observation. The waterfall sound is pretty much gone but I'm still dealing w/ the fairly repetitive gurgle. It appears that I can feel air pushing out of that top vent on the standpipe right after I hear the gurgle. It also seems the left and right sides are alternating that gurgling sound. I used the ball valve to dial down flow and it really didn't make a great deal of a difference. Also put some hose in but no real help.
What appears to be happening is that the water level in the overflow is going down and exposing the two holes in the standpipe. If I can somehow get the level in the overflow to stop rising and falling I'll be good. Any suggestions how to achieve that?
The only way is by feeding it air with some tubing. Large amounts of air are going down the tube and disrupting the water flow, and this is why the water level in the prefilter box rises and falls.
The holes you say are making the noise are the ones you posted a picture of? I would plug them and put holes in the black locline just below the DT waterline instead.
The holes that are making noise (the flushing sound) are actually the two on the adjustable standpipe that returns water. They are both fully extended in height and I was able to get the left one to stop the noise by rerouting the flex hose under the tank going to the sump. The side that is being loud is angled down right to the wet/dry filter without any sagging so I can't really do much more with that hose. I guess if it was in fact the lack of air on the return standpipe wouldn't the left side be equally as problematic?
Ok..just so we are clear "returning water" would mean returning it to the DT, and not the sump. The 2 thinner pipes with the adjustable locline ends on them are considered returns. The larger are drains.
So, you are saying that it's only one of the drains that's making noise?
Yes one of the drains is making noise. I did open up the top cap hole and the surging in the overflow went away. However there is quite a bit of gurgling coming from it now. I did play w/ the opening and the more I closed it the more of that surge I got. I tried to find a happy medium between surge and gurgling and I cannot seem to find one.
I have attached an image of the hose routing for the loud side. And a video of the sound
Well, if I'm reading correctly, the difference between the 2 overflows is that one runs straight down and the other is on an angle, and the one that's straight down is quiet, and the ones that's angled is noisy. Maybe sliding the sump to the middle of the stand and taking some of the angle out of the hose for the right overflow will correct it. I think you can easily remove that shelf.
That's about my last idea. If this is going to be a reef you'll want to get rid of that trickle filter anyway at some point, or at least modify it.
Not exactly. Left side Is dead silent (spirals down to the sump) right is the loud one (Angles directly to sump). It's a bit hard to see but the left side sort of spirals down to the sump as I didn't want it to have it hang down and have to go back up to the sump. Pictures below of Left and right side. (Right on top) I did unsecure the right side return hose and change the angle so it went nearly straight down and then 90 to the sump and it didn't change the gurgling at all so I'm pretty sure it isn't the return causing the issue. I did enlarge the standpipe hole and put a hose in it and I did find a spot where it is acceptable but its still louder than I'd like.