seeing dark brown stains on steps/seats plus randomly on the bottom - seems worse than I can remember, I have attached 2 pics. any recommendation for stain removal procedures. what is best way to start, etc.

My spa-ool has a Pebbletec plaster finish but I suffer from staining periodically also. I have finally been able to determine that it happens when my alkalinity and/or pH are very out of range. It mostly happens when the pH is too high -- in fact that is usually my indicator that it's time to test and adjust! But it can also happen when my alkalinity is too low (which as it happens it was yesterday). Almost without exception if I lower my (too high) pH or I increase my (too low) alkalinity, the stains disappear within about 24 hours. You may want to test your levels. Hope this is of some help.

Identifying the stains as organic or inorganic is the first step. Do you know how? Post back if not and we'll walk you through it.

Aussielady is on to something by recognizing the contribution pH does for the stains she has. because they appear at high pH, that is a VERY good indication those stains are inorganic (metal) and lower pH is always the cure.

don't know how to identify organic vs inorganic stains so all info is welcome

but just opened yesterday so will start checking chlorine and PH levels tomorrow

thinking these are organic stains - is the best way to tell hold tri-chlor tab against it, if it fades in 60 secs its organic?
how to treat if organic? because these stains around the drain have been there 5 or 6 years - they don't fade during the year.
if not organic how to treat ? I am thinking they are organic but not sure
pic titled pool stain 3 - random brown spots in shallow end - new this year
pic titled pool stain 4 - actually crack lines in plaster of a step in deep end swim out - I'm thinking cant do anything for that?
pic titled pool stain 5 - brown spots around drain in deep end - probably leaf related but has been there over 5 years not fading.

looking for opinions....maybe this is it until replastering time?