Hey great idea Shalegac!
Heres a couple that come to mind.
1. If you choose to use a razor blade for acrylic scraping (very dangerous but some do) then bend the blade slightly so you aren't scraping with a straight edge. The slightest mis-pressure on a straight razor will cause the edges to dig in (scratch). A slight bend will remove 40% of the scraping area and will require more passes, but this has not scratched my Mini75 which is 100% acrylic. I only use a razor because a credit card is too large to use in the lower areas of the wall. I have a tool that is a coat hanger with a curved blade JB welded onto the end, I use this to scrape coralline off the lower edges of the tank from time to time.
2. Also, scratches are made in acrylic while cleaning when you drag an organism under your scrape tool; a sabellid worm tube or calcareous particle lodged under a bent blade or card (sometimes the particle is too small to be readily noticed) will scratch just as bad as the side of the blade. Scrape tools safely remove the light green or brown film from the walls, be mindful of the encrusted populations you are scraping. Coralline scraping has also scratched my Mini75 in a few tiny places by getting lodged under the blade.
3. Common products I have submerged in my reef with no ill effects from leaching or contamination:
Paper towels with printed colors (have used them to lay over the water surface for a sec to soak up a bunch of floating detritus and surface film). I used to wonder if the dye in the towels would harm the reef.
Automotive epoxy putty (moldable) and the two-part epoxy gel. Automotive gel super glues, have used probably ten random brands but I stay away from lines that say "wont stick to skin" and the like, this implies they may have accessory chemicals other than cyanoacrylate. I can recall at least 50 occasions where cleaning has broken off frags and the LFS was not open. A Napa or AutoZone will have reef tools at 10pm for emergency use.
Coat hangers (for extension cleaners), plastic of many types (although I couldnt say this is 100% safe experimentation; Ive been lucky so far on the things Ive cut up for plastic sheeting), electrical tape and duct tape adhesive don't seem to harm my pico reefs either. RadioShack rubber grommets and wire ties as well
4. An insulin syringe and a light suspension of Boyd's Chemi-Clean will clear up any 3 inch black spot we have in a sandbed (inject it down into the side of the spot). You don't want this stuff penetrating the entire bed so dilution is critical> but for an unbalanced area where there is accumulated nutrient and rot it works great. I just did it on a two-inch dark spot I had in my reefbowl sandbed.
5. Enough can't be said about using medical hemostats, angled and straight designs, in aquascaping and gluing of Nano Reefs. They also have extensible medical cutters with a tiny scissor blade ideal for cutting deep xenia stalks. Order a kit online for $65 and it will be money well spent.
