How to drop soil pH?

[Flowertime]

I just started a new job and it's night shift and has caused me to neglect my ladies. I noticed that one of the 5 is drinking and eating all it can take and the other 4 take 5 or more days to dry out growing in soil and about the 4th week of flower and also noticed rust spots on most of those and probed the soil and it was about 8.0. Explaining why those 4 are drinking less and the cal-mag deficiency.
What is the best way to drop the soil ph? Just flush until I can achieve 6.5 and feed after? Any suggestions. Thanks alot

 

[Captain goodvibes]

Sulphur lowers soil pH, its commonly used by gardeners and should be available in your local hardware.

 

[013]

I suspect you have a deficiency. All of the seeds in a pack may be related but they are not identical, this simply reinforces the idea that there are different phenotypes in the same pack of seeds. Different phenotypes will behave individually and grow at their own pace etc.

What is in your soil mix?

The ph of potting soils are fixed and buffered with lime when the soil was originally mixed by the manufacturer and before being put into bags for sale or distribution. The proper way to test soil ph is by doing a slurry test. You mentioned a probe, if it is one of the cheapie $12 probes that do a 3 way test (ph, light and moisture meter) they are not accurate.

Do you have (non - blurple) pics that were taken in regular light?