Weeds in composite stone joints

Hello,

my huge problem:
I have a very large property and all the paths and the two terraces are paved with interlocking stones (red old town cobblestones). Everything was done properly, in some places there is even a layer of concrete under the stones. When newly laid, white quartz sand was used in the joints - it looked really great. However, none of that is visible anymore because we can no longer control the weeds growing there now. The property is too large for me to want (and be able) to crawl around on my knees all day to pull them out.
Because of a built-in pond and also because it is forbidden, strong chemicals are not an option either. Using the steam cleaner is also extremely tedious and would have to be repeated frequently.

maybe someone has an idea?
I would be very grateful for any tip.

Best regards

Weeds never come from below as always (where should anything grow there anyway, whether gravel bed or concrete) but from above, accumulating in the joints, brought in by the wind and settling there.

The best and most expensive option: scrape out the joints (or have them scraped) at least 30 mm deep, fill the joints with a joint mortar (if they lie in concrete, use a cement-based joint mortar, i.e. watertight, for gravel, etc., use a water-permeable one, e.g. based on synthetic resin or plant binding agents), jointing (according to the required joint width and load), then you have peace. I can recommend, for example, Terrabond from Rost Systembaustoffe or Stones Baustoffe Stones ECO (these are flexible and do not crumble like a rigid joint).

What else exists, cheaper but a never-ending story: chemically treated joint sand with a pH in which no weed can grow. But over time some joint sand always washes out, everything possible comes flying in from outside and settles on top of the joint, and you have a new nutrient base for weeds again; furthermore, the joint sand loses the changed pH value over time and then it is just normal joint sand again. So every few years sweeping out and refilling the joints is necessary.

Or just live with the weeds, which also stabilize the joints and prevent washing out.

Using a steam cleaner usually makes it worse because the pore surface of the stone becomes rougher and the stone itself thus provides more adhesion for moss, algae, etc.

My neighbor swears by vinegar cleaner... he uses it on his grout and claims to have hardly any weeds there. It is biodegradable, although apparently you have to do it twice a year.

Vinegar works quite well. I use the cheap regular vinegar (so not a cleaner). It's just a bit more natural than chemical products. We have replaced the old town pavement with something new. Especially the old town pavement has very large joints due to the rounded tops. Our new stones are laid very closely and have straight joints.

Does anyone have experience with basalt flour? It is supposed to work well and is not as expensive as all the other special joint sands.

should say: It is prohibited in many places to work with vinegar. And depending on the type of stone, vinegar can also damage the pavement.

You can also do it without bending down using a gas burner.... Just burn the stuff off.