black mold cleaning agents on split face travertine


Silver Supporter
Aug 28, 2012
Houston, TX
Hello to All,

First, Happy Father's Day to all you TFP Dads !

On the spa that spills over to pool, it is split face travertine [off white] and the lower portion towards the pool water, the stone has black mode grown btw stones and w/in holes. No pool water comes in contact w this area on either side but both places are about 3-4" above pool water line.

Does anyone have a recommendation on what is best to kill mold w out damaging stone and if product goes into water, there's no minor issues? Whatever amt of product drips into water/pool, I am sure the dilution rate is so great that there's going to be no real issue.

Again, Happy Father's Day and thanks,


Well-known member
Jun 10, 2014
Roseville, CA
There are other ways, but this is worth a try (test in somewhere for bleaching first):
Make a slurry of 20 mule team borax, and coat the area. Try to keep it damp. Renew it every few days.
The borax should kill it off. It’s used in my house to prevent stinky towels.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Allen has some stuff he swears by for mold and mildew removal. (I’m not sure if it’s safe around the pool, but I’ll ping him and get his thoughts.)

Follow directions and spray on surface. Don’t scrub or rinse. Best applied on a sunny day when it is not going to rain for a day or more. It is environmental safe and does not harm plants or animals. What it does do is change the pH of the surface and kills mold and mildew.