This a 3 step ladder from SR Smith model RLF-24S-3B.
It's noted in their catalog as 304 stainless,
A 316L Marine Grade is available and is recommended for salt pools.
I have seen the rusting, as shown in photo, a few times way before salt pools became popular.
The salt is not the culprit. I have plenty of customers with ladders and rails running on salt that do not have any rust issues.
From the photo, the water appears green. This would indicate the presence of copper in the water which is caused by an acid condition, i.e., low pH and low Total Alkalinity. If there's a heater, it's eating up the exchanger and sending it out to the pool. Anyone using this pool have blonde hair have it turn green after swimming? It happens because of the levels.
pH level should be at 7.6 ppm and TA at 100 ppm (range 80-120 ppm) Free chlorine at 2 ppm is fine.
Even if the salinity level is high, it won't cause this corrosion. There are anodes sold for salt pools to be the sacrificial metal but I've never had a need for them. Salt levels should be between 3000-3400 for the system to work properly and produce chlorine. Output can be regulated to maintain a proper chlorine level.
Interestingly enough, a salt system produces sodium hypochlorite, essentially bleach, which has a high ph value. It drives up the pH and TA slowly and if not kept in check, it can put the pool in scale forming condition. Becomes a basic condition over an acidic condition.
I'd say the homeowner and or the pool service screwed up.
An acidic condition in a pool is one our most common issues as customer never maintain the water, chemistry even they say they do. Usually by this time of the year it shows as we are more than halfway.
It actually looks like the bolts for the treads are rusting. Perhaps they replaced with a non-stainless bolt.
Our work is seasonal and many occasions my customers store their ladders in a shed with a bucket of chlorine and other chems. MANY times when it's time open the pool and we retrieve the ladder(s), the chlorine's fumes from the bucket (BTW, they don't seal completely) eat them apart to the point where they must replaced.
The pool water must tested from a pool store with an electronic tester. We actually have a mobile electronic tester that is super accurate that's used pool side.
Hope this helps.
