Hi, Today I bought the following rocks: (Bright side of the rock) (Dark side of the rock) I rinsed them in boiling water, with a bit of "thickened chlorine bleach gel" (scented), has 30 grams of active chlorine per liter. I tried to get rid of the algae with the white magic sponge and a toothbrush, but didn't work (though the bright side is a dead insect). Left the smaller rocks apart, kept the bigger rock inside the container. Thing is, that large rock already came with algae spots on them, don't want them to suddenly grow in my tank, as my tank may be blessed with purple algae (evidence is purplish water when replaced, and a purple airstone pipe). Though a more central question would be whether those rocks even fit my tank or not. My last pH test indicated around 6.5-7 pH. How will those rocks affect the current pH? Thanks for the help!