Pool Plaster issues

[lmbbuilders]

Hows it going, Im new to this site and I'm having some issues with my pool. Its a 16x32 salt water generator gunite pool installed in June 2015 48" depth with Pentair equipment. I have a DX3 dolphin pool cleaner. I get my water tested regularly, but my Ph goes up very frequently. I have a ph meter installed and I keep it 7.3-7.8. My issue is, I just removed the bag from my dolphin cleaner and installed the cartridge kit and every week when I clean it, I have a pretty good amount of sandy material that is the same color as my plaster. My pool is a year old and im pretty sure this is not normal. As anyone heard of this problem or know what I could do? I'm not sure if this has been doing it as I use to have a bag on the cleaner. My gunite/plaster is Florida Stucco brand. Any advice or information is much appreciate, Thanks in advance.

[Denniswiseman]

What is the calcium hardness of your pool water, it may be taking the calcium out of the plaster
Check out Pool Mathsfor your levels
How do you test your water, pool stores and strips aren't that accurate