Disolved oxygen meter

[watercatwn6535nd]

any one ever mess with a disolved oxygen meter. is there a diy way to build one out there. I heard they were expensive but never looked into them. i'm nver have a issue but i'm curiuos to know what my readings are and how much changing stones and volume effects the reading. at one point i had a stone in under every plant in the system and now i have one duel fuish pump from wally world with two small blue round stones and all seems to be the same.