Krylon paint & PVC

[Stones]

I painted my returns with krylon fusion black and have had them in my tank for about 2 years now. I think I did about 3 coats but I should have sanded the pvc first to help the paint stick better because some cracked off on one return after only a few days of water running through it. Now they look kinda blotchy because my turbo snails came and ate some of the paint off too, but they are nearly covered with coralline now so I don't really mind.