Recommendation for patching plaster?

[crusemm]

I have a spa attached to my in ground pool with a spillover to the pool. I had some leakage issues, and so left it empty for part of the winter. this spring as I am getting ready to repair a broken pipe underground, I emptied the spa and noticed that there are some pieces of plaster breaking loose. So, before the season gets too far along, I was going to patch the plaster, probably with ez patch 1 (non fast setting). I was wondering if anyone had any experience positive/negative and any tips / tricks for using the product. I will attach pics when I get home and get a chance to take some. Thanks.
https://lh3.googleusercontent.com/-ZDk9 ... 25_376.jpg