Don't use porous travertine if you want to ''clean'' them. They will never be clean. The holes and crevices hold dirt. You would need to use a scrub brush and pH neutral stone cleaner weekly on the whole acreage. And you would still never get the grime out of the holes. Love it dirty and natural or don't do it.

Have a stone maintenance company do it on a regular basis (they have the right equipment to clean natural stone and will then reseal it).

Being perfectly honest , all you need is pressure washer...It will never hurt your travertine and also take all the dirt right out. It is natural stone so clean it naturally.

Never use anything acidic that will ruin the travertine or in fact any natural stone.

If you have not chosen your travertine pavers you may want to see this travertine pool deck paver collections before making your final decision.

Let me know if you have any other questions.