I have a deck drain from my pool area which is enclosed in a screen. The drain is a 4" PVC pipe that drains to the outside of the house into a gravel pit.
I noticed quite a bit of no-see-ums in the screen enclosure area, and this should not happen since it's screened in with insect screen that no-see-ums cannot pass through. I am suspecting they are coming up from the deck drain pipe that drains into the gravel pit. I guess the only way to stop this is to either cover the outlet with a screen mesh material but that would inhibit the flow when it rains and also trap debris. The other option is to install a p-trap in the drain line, but do they make a p-trap for 4" PVC pipes?
Thanks,
MC