These include cadmium, lead, gallium arsenide, copper-indium-gallium-diselenide, hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride, 1,1,1-trichloroethane, and acetone.

I tried fertilizing it with muriatic acid, even cut the roots so it could absorb the fertilizer better.

Power washing and some type of acid wash plus power washing did not remove the black coloration from the otherwise standard concrete color floor.

The water could be acidic , you could have some electrolosis .  

If it's on concrete I like acid stained floorsIt's relatively easy to do and cheaper...sorry, less expensive... than vinyl, or laminate Looks amazing Very popular and desirable in my area.Seems like a good selling point and I see more and more new constructions going with it all the time If you're renting it's perfect 1 time investment of time and labor and it's done It's my go to when possible There's a ton of DIY resources on YouTube that I've used

So i figured go for a better class of asset while i am still new and a little uncertain of macro factors (to avoid heartache/acidity/deep paper loss in the short term).

I have used some industrial glass cleaner and tried vinegar for it's acidity, to no avail.

Should I just treat the place with boric acid and traps for a bit before we start the rehab to be safe, or are german roaches persistent enough that you would recommend hiring a professional to come treat?  

If it passes this RE acid test, then cash flow is considered further as a plus.If you buy and hold for a few years, sell and move up, at the end you'll have equity in better properties that can be soldfor note income as opposed to being retired, yet working as a landlord!

See if you can get a quote to acid wash that pool.