Ok so finally water testing tank and the dorso drain is NOISY!! Gurgling and sucking noises, played around with return pump pressure but nothing. Watched several videos on them and noticed none of the diy ones look like mine. Here is a pic of mine and you will see the holes I refer to around the top near the T. These holes seem to be where the siphon and noise is coming from, can anyone shed any light on this please?
