Rockwool PH 8!

I got some rockwool cubes I was told were ph-neutral. Just earlier today I started propagating seeds in them. It struck me I also could investigate their ph-value with the water I used to soak them in... and heck, it was way up in 8. I immediately rinced them with water ph'd to 6 (with vinegar). Later today I intend to redo the test and see if the situation improves.
Just so you know. Even though the store says rockwool is ph-neutral, it isn't always true.

Did you use distilled water to soak them in?

Neutral doesn't necessarily mean perfectly at seven too. It could be a range of say six to eight.

Rock wool needs to be kept in the range 5.2-6.2 optimum being 5.5.

Pre soaking for 24hours in pH 5.5 is usually the best way.

As the rockwool dries its pH value increases drastically!

Keep it moist.




J

I switched to rapid rooters

It seems to be stable at slightly below 5.5. It'll go up a little over time, so no panic right now.
Until now I've first drowned seeds in water before planting them directly into soil, but I intend to go hydro from now on. That's why I picked rockwool this time.
Beyond that everything noted. I'll make sure not to let the rockwool dry.