Just visiting the forum whilst getting ready for work. Haven't got time to answer anything in detail but....ditch the BAL grip.
I'm a great lover of BAL, i always use it where i can. I don't like using tubbed adhesive anyway, but in my opinion the BAL grip is absoluet garbage. You would proberbly get on better using the toppfix slowset flexible on the walls. Yes you have to mix it up yourself, but it's 100x easier to use than BAL grip.
Not quite sure why people even use tub adhesive, obviously they havent take off tiles where water has got to the adhesive over time it goes back to paste. Cement based in a bag, its the only correct way....
What would you recommend as a replacement to the bal grip? It will be the area that will be in the shower. It's photos 3&4 above. The substrate is Hardie 500 with plastic behind. I'd like to feel confident about these tiles!
Thanks