I always start of will calmag between .2-.4 EC depending on the stage of the grow (coco). I always keep between 10-15 gallons RO on hand and the reservoir is not air tight so the PH does drop to around 5.5 as the RO sucks up co2. Once I add the calmag the PH starts creeping back towards 7. If you just let it sit within 24 hours it should mostly stabilize or if you bubble it with some air stones that will accelerate the process.
Your nutrients will also affect PH so keep that in mind. I find if I add calmag then add nutrients then bubble with air stones for a few hours I get a very ph stable nutrient solution between 5.8-6 that doesn’t need any adjustment. People get big PH swings when they adjust un-buffered RO or when they PH adjust it before the PH has had a chance to stabilize after adding calmag and nutrients.
Buffer your RO with about 100ppm/0.2 EC calmag, give it some time to stabilize and you are good to go.
Your nutrients will also affect PH so keep that in mind. I find if I add calmag then add nutrients then bubble with air stones for a few hours I get a very ph stable nutrient solution between 5.8-6 that doesn’t need any adjustment. People get big PH swings when they adjust un-buffered RO or when they PH adjust it before the PH has had a chance to stabilize after adding calmag and nutrients.
Buffer your RO with about 100ppm/0.2 EC calmag, give it some time to stabilize and you are good to go.
