Uh, I'm not sure about the OTO or DPD.... I fill the container with all the shades of yellow up to the line and put in 5 drops of the tester? .
Do you have muriatic acid on hand? Add 2 or 3 ounces of 31.45%, circulate for 30 minutes, and check again.Water looks clear! And I'm not sure if this has anything to do with the current issue, but my ph has been at 8.4 and no matter how much sodium bisulfate I add it wo t go down. ?![]()