[shammy davis jnr]

can u use sure flow back pacs for acid descaling acid ?
our if any of u guys now what is a good back pack manual operation for this
dont mater if its pricey just good quality so it will last at least 4 gallon
also if any you guys done this before are you better with a smaller back pack and sprayer ?

[jeff1]

Shammy the back packs are built to put all types of nasties in,  so I'm sure a descaler won't hurt them.

If in doubt go and buy one of those cheap hand pumped ones from B&Q, they will certainly do your 4 gallons.