COCO medium
G.H nuts
Runoff water PH is keep going up...
1st I runoff with PH 6.0 / 1 PPM and runoff water came out 6.9 / 160PPM
2nd flush with 5.0 PH came out 7.0
3rd flush with 5.0 PH came out 7.1
4th flush with 5.0 PH came out 7.2
why is it keep going up?? how to solve!??!