The many times I've acid washed my pool, over 24 years, I used baking soda to neutralize the collecting pool (probably lower pH than from soaking something - from rinsing the plaster with a lot of water but still pretty acidic) in the deep end and then pump it to the woods. For an acid wash of my pool there are many, many, many, "acid pools", during the process, that have to be pumped out. I haven't seen any problems with the native plants. And, yes, it takes a lot of lbs of baking soda but certainly takes care of the problem. When I've soaked the spa cartridges in MA/water I usually throw it into the pool, but my pool needs almost daily MA additions especially with fountain and keeping the pH at or below 7.2.
When you add the baking soda it will foam up and out of container so best to do it on gravel or dirt area; not a surface you want to change colors. But I must confess, when I soak cartridges, and don't put it in the pool, I do it on my Trex deck and add the BS in small additions so it doesn't foam over, most of the time, and keep a hose going at the base of the bucket.
I use loads of white vinegar (more acid than most colored vinegars) and BS around the house for cleaning. It's great for clearing out a slow drain and trap. Put gobs of baking soda in the drain, add vinegar, and then flush with very hot, but not boiling, water.
Another use would be to put it in a spray bottle, if you can filter particles out, and spray on some weeds, grasses, etc. It burns the plant when the sun hits it in a couple of days. Or dump it on a whole area of pest/weed plants. You have to get it on the green part of plant. I use garden white vinegar, very acidic, 20%, for some spot weed/pest plant killing. I feel better about using that in areas where the dogs might munch on plants. It doesn't work so well for poison ivy. You have to resort to the heavy stuff for that and, so far, I've only been able to wipe it out for one season and then it grows right back the next spring.
gg=alice