Good thinking with the PVC, they'll really appreciate the cover. I created a little jungle gym out of 6 8" sections of 1.5" PVC (left over from my sump plumbing) and some epoxy. I put two pipes on the bottom this way:
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Then laid three on top of those, one at each end, this way:
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And one final pipe on top this way:
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So the entire structure looks like this from the side:
. . O
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O......O
(excuse the dots, that's just so the spacing came out right)
And like this from the other side:
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O O O
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The pipes are just attached to one another with blobs of epoxy - not pretty, but it does the trick and it's lasted a long time and shows no sign of coming apart.
The fish absolutely love it. I QT everything in hypo for six weeks, and I've noticed that fish in the QT seem much more relaxed with this structure in the tank than they did with the other bits of pipe I used to place on the bottom before I had the 'gym' - I think it's the levels, and how many holes there are. It's like having a large piece of rock in the tank - several fish can hide at the same time, either inside or between the pipes, so there's no competition for shelter. It's also easy to sterilize, I just bleach it along with the tank and filter when I'm done using the QT.
I wish you the best of luck with your clowns. I recently babysat four clowns for a friend, and two ended up dying of the same symptoms you're describing. They looked a little down and out when they arrived, and within days they had stopped eating, started breathing rapidly, and nothing we did worked. We tried prazi-pro, metronidazole, fed them with garlic (while they were still eating) but unfortunately, for us it was too late. I hope you can save yours, fingers crossed.