I planted in soil with ph of 6-6.5 and watered with mineral water of ph 4. Added some ferts and it's now 4/5 weeks. Now the ph is 7.5-8.0. How does that work?

I'm thinking of transplanting them again, whats the best soil to use to have a stable ph? Seen some coco soil (said coco but felt like a soil !?) in a local garden centre. I live in Spain and it's hard to get things especially if you do not know enough Spanish!!!

What about soil for cactus, there is a lot of that here?

Any advice will be appreciated.

as your plants feed and expell their wastes your PH will rise.
This is true in all types of growing, aero, hydro and soil.
Im sure your growing medium is fine, just make sure to stay on top of the soil PH and adjust as needed.

Good Luck

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When we reject the mindset that life is race, we loosen the stranglehold which education has over us. Thus freed, we might begin to learn things for more authentic and natural reasons. We may then begin to fully enjoy the delight of discovery, of intellectual stimulation, of the deep and ever-changing diversity and endless wonder our world.

Also, i wouldnt recommend transplanting unless your plants need a bigger pot. as that will will do more damage now, than a slightly high PH

__________________
When we reject the mindset that life is race, we loosen the stranglehold which education has over us. Thus freed, we might begin to learn things for more authentic and natural reasons. We may then begin to fully enjoy the delight of discovery, of intellectual stimulation, of the deep and ever-changing diversity and endless wonder our world.

I'm with Luck. Even If you planted one week ago your Ph could have changed, but there is no reason to transplant just because your Ph changed. It should be checked regularly to maintain it. Only transplant if you need a bigger pot. Ph can change by adding nutrients & should be checked often.