Easier SPS

[trilinearmipmap]

I have a T5-lit mixed reef: softies, LPS, BTA's, and for SPS I have Montipora digitata and Montipora capricornis.

I have no calcium reactor, I do kalk plus DIY 2-part, I am not very rigorous about 2-part additions and water testing, my calcium and Alk level are usually pretty low (Ca anywhere from 330 to 380, alk usually around 7). Despite this the Montiporas have thrived.

What other easy SPS would be good to try?

Also has anyone had success attaching corals to the back wall of their tank or overflow box? I am running out of real estate in my tank.