Can I flush with ph7 water?

The suggested pH range for a weed is around 5.8 to 6.8 pH. You will usually flush about two weeks before flower or if you've given it a major toxicity. You can use lemon juice to lower the pH of water or feed; If you put 1⁄8 tsp (0.62 mL) of lemon juice in 1 US gal (3,800 mL) of water, you can lower the pH by about 1.5 You can use this as a general rule, but I would suggest just adding a few drops; and checking pH after. Unless you have a microbe nutrient, don't do this too often because lemon juice can act as an antimicrobial which will kill both bad and beneficial bacteria. Using it rarely to readjust the soil pH is no problem though.