So my overflow is/was rather noisy for a herbie. The herbie part of it was working fine but what ended up happening was the eggcrate grill of the overflow created 15 streams that poured into the overflow causing quite splash. It wasn't so bad when the water level in the overflow box was higher up, but when it was half way full it was quite noisy. I had to take action and this is what I came up with.
It is simply a cut piece of filter floss that I draped over a sheet of egg crate inside the overflow box. The water flows over onto the filter floss and then gently flows down. It is quite an effective silencer. No matter what the level of the water is in the overflow box, it is dead silent now.
Here you can see all those little streams that used to gush into the overflow box. Now they gently flow.
