I am sure everyone heard the story about "Ars# Hole that wanted to be boss", the siphon world is no differ. Tweak all you like the top part, if the bottom outlet is not happy then you are in for a trouble.
Apart from having a reliable siphon, good aeration is key important for a successful aquaponics system, instead of using a separate aeration pump it is beneficial to make use of the return water to aerate the fish tank.
What we need to do is to get more from what already given from water splash, introducing turbulence and giving air a chance to mix in will do just that and at the same time reduce noise from returning water.
It was some time that I looked at the Siphon Outlet, it's the unsung hero of aquaponics that been neglected since its work so well.
I did some work due to high water problem then rework to improve aeration and noise reduction, all the work done so far is with regards to variations of the double elbow. Its time to go straight.
I know that we need some form of restriction to create the back pressure making siphon operation more reliable and able to start at lower water inflow as compared to no restriction as in some test I did previously in search for a silence siphon.
It's Christmas today, I am at home. So its time to do some tweaking. I am making the outlet straight to suit some installation where it's needed to be that way and at the same time trying to maintain maximum aeration with low noise level from the splash.
Above siphon outlet works well and hardly need any improvement, but on certain installation it just need to be straight. Multiple siphon going into a manifold for example will require a straight outlet to make it easier for system layout and reduce chances of leak.
Having a straight down pipe with 25 mm tube as below, does not work well. It requires more inflow to start a siphon so its not a good option.
We need restriction to make it work with less water, either in the form of an elbow or some other means. Below a simple restrictor that I made few years back.
This time I decide to use a reducer making the restriction and try to manipulate it to give same or more aeration and less noise on the set. Below is the first trial with a simple 25 to 20 reducer.
Addition of a 20 mm tube with holes to provide better aeration and noise reduction.
Making a venturi below with 2 reducer back to back, hoping it can create improvement and making the final outlet same size as initial which is 25 mm.
Above outlet has been shortened to accommodate and may need to be further reduce its length on some installation.
I replaced three of my growbed double elbow outlet to test out variations of straight outlet to see how it perform over time. It need to be tested with varying water inflow to at least comparable to that of the double elbow outlet rate.
So there goes, I will be testing these for next few months before I can make this outlet for someone else.