The tenant is responsible for opening/closing and chemicals to maintain the pool.  

Buyer is a smart guy....chemical engineer...but just not dealing with these kinds of things every day like I am.....so there is the value of your great agent.   

I am more concerned about actual chemical contamination or criminals who lived in the house that a parent owned showing up after they get out of jail.  

Older homes especially have a lot of chemicals/dust/asbestos/lead in them - this is not good to breathe in for you or your family. 

Washes will likely need an environmental survey that can be complex. a great person to connect with would be a chemical supplier.

Any cement previously drilled through where a termite company injected their chemical and patched the concrete?

@Dushyant Ravi Yes, agency debt comes with the lowest rates but much harsher prepayment penalties in either case. 

Even if the grout is sealed, the tenants do not care enough to clean the mess in a timely manner, the stuff in it will stain the grout and with the chemicals and pressure wash the seal will fade/go away.  

There is always someone who will dump chemicals all over the place and call it a treatment, sometimes this works.

If you get out towards Pasadena area, it’s all oil refineries and chemical plants.