Adrian

Danny,
At the risk of sound a bit anally proactive....
If you get to that stage of a project and have never done it. It's time to hire a professional.
Your fence..... totally doable by yourself. It can be difficult .... but you have done your research so far.
However, when you are faced with proper tarping, landscape protection, PPE, and the cost of whatever products you use.
You might as well hire a professional who already has the gear at his disposal.
In fact in some cases you could potentially pay more to do it yourself in the long run.
...... you should only be spraying that acid as a neutralizer for the stripper and or cleaner that needs balanced. Not as a cleaner itself.

Max, welcome to TGS.
If I understand correctly, your deck is just a week old. Right?
When you say "roofed", it has a ceiling, arbor or awning over the deck. Right?
Your karcher is enough to clean and prep the deck as a DIYer, but, why, it is brand new?
There should be no prep required if wood is brand new. However I would suggest waiting for the wood to acclimate to it's new environment a while.
That's just my take on it. Others may say different.
Personally I would wait until next spring to treat the deck since it is brand new.
The stain will adhere much better. IMO.
A simple per carb cleaning in the spring is all you will need to prep the deck. Then stain it.
I have used a wagner paint crew many yrs. ago and it worked fine for what I needed to spray. I also ran a longer supply tube from the wagner directly into the stain jug.
The container on the wag was way too small and requires refill too often to suit me.
Many contractors here swear by the AC stain. You can contact some of the suppliers here on this forum and request some samples to test, just to be sure of the product you want to use.
Sidenote: you will want to dial down your psi on the Karcher to about 800 psi so no damage occurs to the wood.
again.... welcome to TGS.
another sidenote: this is the first year I have missed the balloon fest in ABQ. Man, what an awesome event. So much fun. esp. at night with the burnoff displays. So freaking cooooooool.

If you have already stripped and sanded and you still have evidence of silicone, replace or flip the boards.
The wood in ATL is usu. PT pine or Cedar which is pretty soft wood which will "drink" the silicone base meaning it penetrates deep.
.... flip 'em and go with an oil based stain. It's more managable IMO.

... or it could be a core section from a larger stone that has ions of mineral deposit buildup. The deeper you dig the more you expose. Texas has layers of cleeche SP? before you get to any layers of solid rock.
Cool to see another lone star on the board.

I post..... some read...... rarely get comments..... not really sure how I am viewed on this site..... but here goes John.
I don't know you personally, other than this site. You seem very intelligent and knowledgable in this field not to mention mature.
Either bury the hatchet or simply ignore, BUT, don't let it rob you of a great experience like a roundtable.
I have only been to one RT in ATL. and it was worth it a thousand times over.
I wish there were some here in the lone star state (HOUSTON ESP.) I would be there everytime.
Being a bigger person makes you a more humble person which commands respect and hopefully closure to your issues with this person.

PWing for the first 3 years, then added wood resto 2 years ago.
It seems that PWing just naturally branches off into the woody category where it can actually triple the income over PWing alone ( after much learning ).
Repairs automatically branched off from the resto add on.