I am designing a 50' pipeline through a levee connecting a tidal slough and a managed pond. The pipe is a 36" diameter solid wall HDPE pipe with combination slide/flap gates on both sides. I have had Waterman gates in the past with custom diameter sleeves to fit inside of HDPE. However, I was...
Make sure the tank is gas tight. This might be as simple as sealing or repacing your lids. Also, Orenco Systems makes a carbon filter that slips on the end of PVC pipe for the vent pipe on your roof. If worse comes to worse you can add a small fan to actively vent the system...