pH down....lemon juice/vinegar/phosphoric acid............pH up baking soda/bicarbonated soda/garden lime. on the ph down i have used superthrive mixed 1ml to 1ltr then use that mixture to bring the ph down this was the most stable ph down and kept the pH stable for longest while vinegar dosent keep it stable to long but hey you gotta use what you can get.best of luck .davey