Tri-level deck with old and new wood Help pick stain/stripping/cleaning products.

Hi,

I am getting ready to stain my deck so I would like to get some advice on what kind of cleansers and stain I should use.   I live in Maryland.  We have 3 levels of decking.  It is all pressure treated pine wood in our deck.  Some of the wood is new (installed summer/fall 2022), and some of the wood is 20-25yrs old.  The older wood had Behr (I think semi transparent) stain which held really well to the spindles of the railings, however it peeled considerably.  I will make specific comments to each level of the deck.

Above is the top deck- full sun.  It has brand new as of fall 2022.  It has never been washed or stained.  We basically just replaced the old board that were here, so the supports under it are probably 25years old and stained with an unknown stain.

These are the steps leading down to the mid level deck. These steps are stained with Behr semi transparent probably 5-10 yrs ago.  I did not clean these steps yet.  You can sort of see our mid level deck here.   The spindles of the railing are still stained with Behr semi transparent.  We put new wood on the top of the railing in Aug 2022 and replaced some of the spindles that had holes in them.

This is our mid level deck - full sun.  We ripped out an old hot tub and replaced the middle boards from about the blue chair to the outer edge of the round table (2 pictures above).  These boards were installed in Aug 2022, but the other surrounding boards are about 23 years old.  The stain on the old boards (Behr semi transparent) was applied maybe 5-10yrs ago.  I already tried to remove this stain on the outer old boards and railing on the right of this picture with Behr wood stain and finish stripper.  The left side old boards have not been stripped or washed yet.

I tried to strip the outer boards and railings last fall with Behr wood stain and finish stripper.  As you can see, there are some patches of stain remaining.  I did not use a power washer to do the job, just my strongest sprayer setting on my hose.

We have some stuff here on some of the new boards we installed in Aug 2022.  Not sure what this residue is.

Here are some of the Behr semi-transparent stained railings, about 23 years old, with the stain holding well.  There is a new railing top though put in in August 2022

These are the steps leading to the lower deck, stained maybe 5-10 yrs ago with Behr semi transparent

Here are two pictures of our lower deck.  We did not feel like replacing these boards yet.  However we took some of our nicer 23 yr old boards flipped them over to patch up the most rotting boards from the lower deck.  These are the oldest boards, probably installed around 1995-1998.  The Behr semi transparent stain is peeling on this deck horrendously.  That stain was applied maybe 5-10 yrs ago.   I have the feeling that in the next years to come, we may replace this deck but we did not have the $ to do it yet.

I would love to have another semi transparent stain if possible for all the deck levels, even if the mid level deck doesn't look picture perfect with the mix of old and new boards.  Please advise on cleaning solutions, strippers, and deck stain.  My husband would prefer to have products that we can go to a physical store to buy, however I want whatever is best and most easy to maintain.  

Thanks!!

Sarah