What are you using it for? to lower PH?
i've been getting a few different ph readings in my ffof soil this grow. I us a hanna digital meter. This grow has gone well with a few ph probs and thought that with the lime in the soil -plants medium wil be ok next time round. I've been reading that a lot of people are have similiar issues with ffof being unstable. Allways ph water to 6.5- run off is usualy at 6.6-this is y i'm leaning towards my meter as the problem. Harvesting this week of Sensi BB Going to replace batts for next grow.