I needed to add a couple caves to my bare-bottom fiberglass tank as I am moving my P. niger into it soon. I thought about clay drainage tile, but it's hard to find these days (plus I wasn't sure about the chemistry - Dr. Joe?). Then I remembered these scraps of 8" PVC that have been laying around the place for about 10 years (I picked them out of the dumpster at a construction site).
I used a Roto-Zip to cut the ends in a free-form shape. Then I cut the bottom out of each "cave" with a circular saw. I added a "side-door" to one as an afterthought. Next I used my angle-grinder with a coarse sandpaper wheel to bevel/round all the cut edges. I used a palm sander to remove the oxidation from the outside. Finally I gave them a good cleaning with a Scotch-Brite pad and water.
I used a Roto-Zip to cut the ends in a free-form shape. Then I cut the bottom out of each "cave" with a circular saw. I added a "side-door" to one as an afterthought. Next I used my angle-grinder with a coarse sandpaper wheel to bevel/round all the cut edges. I used a palm sander to remove the oxidation from the outside. Finally I gave them a good cleaning with a Scotch-Brite pad and water.
