Mix to get rid of green algae on slabs?

[nauseous]

Yes and you can use soda crystals on your pots and pans too.
The point is why would vets all over the world recommend to use soda crystals solution on you cat, to induce vomiting in an emergency, if tip toeing over it on a damp drive and licking its paws afterwards will poison it?

 

[StephenOak]

A chemical that is generally used as a biocide, however...

Are you & @nauseous talking about the same thing?

@nauseous is talking about sodium carbonate (and its hydrates) which has many uses and a biocide is a very minor one. Its main uses are (according to Wikipedia), glass making, water softening, as a food additive and as a general purpose alkali.

From the same source, the LD50 is 4g/kg which is not a particularly low figure. For comparison, the LD50 for NaCl (table salt) and for citric acid is 3g/kg.

 

[JohnD]

I'm talking about

5L of 50% benzalkonium chloride

A chemical that is generally used as a biocide

findings vary " Eye contact. Acute oral toxicity (LD50): 240 mg/kg [Rat]. (Benzalkonium chloride). Very hazardous in case of skin contact (irritant)..."
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&cad=rja&uact=8&ved=2ahUKEwjI_tTox-jmAhXBiFwKHdY0BBYQFjALegQIAxAC&url=https://www.spectrumchemical.com/MSDS/BAK50.pdf&usg=AOvVaw3oQTO304Cmf1N3I6trh0wh

 

[StephenOak]

I'm talking about

5L of 50% benzalkonium chloride

Well I don't think that anyone would have concluded that. There were two posts inbetween me mentioning benzalkonium chloride and you saying

It is also poisonous,

both of which were talking about soda crystals.

When you change the subject it is only common sense to say what you are talking about rather than just hoping that people will guess correctly.

And in post #14 @nauseous explicitly mentioned soda crystals and you responded to this by talking about a biocide. So it was obvious to you that you had confused, at least, him. That was the time to clarify things.

 

[nauseous]

Thanks -- got the other half to pick some up from Wilko yesterday so will give it a go at the weekend. To be honest it's mostly algae.

Did it go alright?

 

[cwhaley]

Did it go alright?

Made no difference whatsoever. I mixed it into warm water in high concentration but saw no effect after several hours so I just pressure-washed the drive. That did a great job but obviously I'll be doing it again later this year.