PH hindered by rubbermaid totes?

After a few days the empty barrels waters Ph had risen to almost 9. I emptied the barrel and set it to dry out. In a few hours the inside was completely white. The DIY rocks move to the 55gallon aquarium ph dropped to 8.2. I scraped some of the white residue put it in a small jar of water Ph went to 9.0. What ever precipitated out of the rocks must be my issue. Glad I figured it out. (I think)

 

I made some DIY rocks and it took almost 3 months for all of the salt to disappear and the PH to drop. I put them in my tank after the water would sit on them for a week and stay below 8.0.
Concrete as lye and limestone in it. Totally natural for it to be really basic.