A reading through was taken 6 inches from Every single air pump. To stay away from the vibrations in the air pump affecting The end result, the meter was held from the air. I'm a distributor to get a Japanese pump identified as FujiMAC. It's a high quality wastewater pump https://tropical-aquarium-heater71368.liberty-blog.com/19826600/the-5-second-trick-for-aquarium-supplies-online