It's way more complicated than this but this is how I understand it .
"Cheaper" biocides (other than Algoclear) contain a alcohol . This is used in the extraction of the Quats from the soya bean.
It would be easier to think of it as olive oil.
It's all olive oil for use in cooking.
Your Algo clear is the first press….the extra virgin. The "rest" are left pressed again… think cheaper supermarket brands.
Back to to Quats…After Algoclear has pressed what it wants out ,Alcohol is then added to the remaining soya beans , this desolves the remaining oil (a solvent) and whats remaining quats is then extracted.
So All Biocides are not the same but they most will do the same job (very well). They all need to be approved by the HSE so we can use them. It is technically illegal to mix your own as it has no Hse number or Data sheets supporting it's chemical composition.
We need the "paperwork " back up in the event of something going wrong….it will not prevent things going wrong.
With these products that are approved there will be a specific set of instructions on the dangers of the product, mix ratio's it's intended use. These will be backed up by a manufacturers product support.
Read the label/data sheet…most don't lie.
Active Ingredients: The active ingredients of the product are listed as percentages and are the chemicals responsible for the control of the microorganisms.
Other (or “Inert”) Ingredients: Inactive ingredients are often grouped into one statement and include items such as soaps or detergents, dyes or coloring agents, fragrances, and water.
Am I boring you?
I am not sure what Kevins bio-cide is called…but he does have one and it works well.
I could go on and provide you with a whole list of Quats based chemicals which work out cheaper….But you would not have the support from the supplier you sometimes need.
Algoclear being the most expensive on the market is still cheap to use . A litre is approx £15 , this mixed with 30 litrs of water will give you approx 100sqm of render cleaning chemical. I would suggest that the going rate in some areas could be around £3/4 per sqm. Benz and Softwash solutions etc are even cheaper I think .You go and do the maths….Quats is cheap. It works on most growth and is relativly safe to use.