Question
Sean,
We have mold (I assume it is mold)growing between our pavers on the patio. What can I use to kill it and insure it does not return. Patio is in partial shade and pavers were set in sand. Thank you!

Answer
If it is between your pavers and it is greenish it is probably not mold, it is more likely a moss and there is nothing wrong with that except maybe aesthetically, if you don't like it. Its certainly not bad for the paver our your health. If its gray or black and darkens the pavers, that might be mold.

The issue is almost definitely too much shade and or moisture or both.

Either way there is no environmentally friendly way to remove this other than by hand, scraping it away with a trowel or something of the like.

You could try some fungicides or even diluted bleach but that could affect your pavers so check a small sample area first.

Good Luck

Sean J Murphy, LA,ISA, LEED AP
Please check out my blogs and articles on landscape topics like this on my websites.
http://www.seanjmurphy.com
http://amenityarchitects.com