I have my DIY skimmer up and running. I was able to deliver small bubbles with a PH. It has been about 18 hours and no foaming. Im not sure where to make the water column end. I have read that it can take a few days to get the lg bubbles and foaming to start. Any one know why ? Right now the water colum ends about at the bottom of the neck for the skimmer cup. This is also about 3 inches above the return for the skimmer. Any ideas would be appreciated.