We have drained and cleaned our pool which is a concrete bottom with fiberglass panel walls. We have some "bubbling" or almost "warts" that have small cracks in the fiberglass walls that have dirty water that leak out of them since we drained the pool. I went through and cleaned them and then put a small amount of marine grade caulk on each spot thinking this would seal the crack in each spot before we paint.... however a few days later the sealant/caulk has bubbled and turned black - looks like water is bubbling behind the seal. I dont think the panels need replaced but would like to know if anyone has experienced this and what we should do before proceeding with paint this weekend. Our pool is in fairly good shape and we thought just need a new paint job... but now this seems to have started and gotten worse since we drained the pool last week. We are located in Northern Indiana so we only have a few short months in the summer that we use our pool.... Any suggestions on how to repair these tiny cracks are appreciated!