Brick block patio moss and weed killer.

Bleach will kill most things, but will leach into nearby flower beds and lawns possibly doing damage to wanted plants. BAC (benzalkonium chloride) was the best thing for killing moss, but wasn't cheap. I used to use it at a lower concentration (around 5%) than that recommended (10

- 12%) and it seemed to work just as well.

Neither of the above are "approved" biocides. The only legal product AFAAIK for killing moss is ferrous sulphate; it's fine for use on lawns, but don't get it on anything else unless you like rust-coloured stains which are effectively impossible to remove.

The path weedkillers will work on normal weeds, but won't work for anywhere near as long as they say they will. For a quickish (2 - 3 weeks to work) knockdown of those plants use glyphosate.

Have you pressure washed it?

No, I don't have a pressure washer and I though that was not supposed to be a good idea as it blasts the sand out of the joints?

How much of a stickler for rules are you?

Benzalmonium chloride and a pressure washer

My bad,,,]

Benzalkonium chloride

As used in 'Dettol' etc.

Normal "pathclear" will also kill moss, but it's the only thing that is effective against black lichen

It is a fairly benign thing used in many medical preparations You don't need the pressure washer, just spread it on and wait for heavy rain (I *painted* my stone patio with 50:50 bleach and BC and juts left it)

More work than various weedkillers, but a Sheen X300 Flame Gun Weed Burner would do the job without any toxic run off into flower beds.

Expensive now I see. I 'inherited' mine when we moved here.

BAC50 is around £31 per 5 litres on Ebay. Bac50 is a 50% solution of Benzalkonium Chloride which can be diluted with water.

Apply a 10% solution and let it dry, moss will turn brown and die within a day or two and just let the rain remove the debris over the following months.

Products such as patio magic are Benzalkonium Chloride but at a much lower concentration (7%) so just an expensive way of buying BAC.

My experience differs. Flame guns are good at removing surface leaves but don't tend to kill the roots, especially with deep rooted weeds. Many weeds will re-appear shortly afterwards. I also found that the flame had to be held in place for some time making "weeding" a large area a lengthy and tedious process.

You need a weed killer that kills the roots and many of the home DIY remedies tend to give a near instant result but don't kill the roots which are protected by the paving blocks.

Thanks, I've ordered some, eBay 297090870938. They recommend "Ground Surfaces: 1:30 (1 part product to 30 parts water)" which would be about

Was your dilution 10% of the supplied 50% (ie 5%) or actual 10%?

As I said I painted mine on with a brush, mostly neat and let the rain do the dilution

Surely, the point is that the sand is no longer sand. It's a mixture of sand and soil, with seeds and roots incorporated. You really do want to remove a bit of it at least, so as to cleanse the area. It's up to you whether you do that by hand or with a pressure washer.

Sand is cheap, and it's easy to brush some more into the gaps.

The main issue I found many years ago was that the sand which was washed out ran down in the stream of water and entered the drain by the garage. It didn't block it, but I was concerned that it might.

The same preservative that is used in many medical eye drops like "Cosopt" and Latanoprost, so if you also have to use these and have reacted to the BAC (so need to use the preservative-free variants), be careful and wear eye protection.