This is a question that I get asked a lot. There are many products out there and yes they do work but which is most cost effective.
Most of them you Wet the surface with the solution and walk away. I have another solution. I could go on about the chemical make-up of the available products, (which incidentally are very similar) but most people are unaware of the cost per litre of the Made up product.
Some of the products are diluted so that they bare able to be sent via a regular courier and not dangerous goods. Also the warning level changes when you dilute the solution. An example of this is Bleach or Sodium Hypochlorite , Chemical formula: NaOCl in it’s undiluted form is highly corrosive and requires a lot of care in using it, when diluted into regular bleach that is sold in the Supermarkets, it is not as dangerous. These same goes with Moss and Mold treatment. Look up google and type in your regular product with “MSDS Sheet” after it and you will be surprised. “n-dodecyl/tetradecyl-n n-dimethyl benzyl ammonium chloride” is a mouthful but that is the active ingredient in these products. Undiluted, not friendly. I can source a product that has the same active ingredient but is less diluted therefore making it a lot more cost effective