Spawning BN's is pretty easy IMHO. Water quality is important and indigo's method of using hornwort to extract excess nitrates is pretty good! My spawning set-up is easy-peasy. I have one pair in a 20 high. I run a sponge filter and a HOT filter with a sponge on the intake tube. Water changes are very regular (twice a week) and at least 20% of the tank when there aren't any fry. Once there are fry, water changes go to every other day since I leave the fry with the parents until the next spawn leaves the cave. For caves, I use simple easy DIY tile caves. Six inches in length, about an inch and a half wide and an inch high. Silicone the pieces together and voila, instant ancistrus honeymoon suite. I've experimented with larger caves but they seem to like the closer confines, often ignoring the larger caves for one that's more snug. I use R/O water exclusively. TDS is very low and it's easier for me to measure other water quality issues. I'll try and take a few pics of my breeding set-up and post them. Substrate is regular old fish gravel, although my browns are moving to a silica sand tank this week. I keep temps a little lower in the breeding tanks, usually about 74-76° and this works very well for me. My grow out tank for the babies is another 20 gallon, no substrate, sponge filter, and a HOT filter, again with a sponge on the intake tube. I keep that tank at 74° for higher O2 levels since there's usually at least 50 or so babies in there at any one time. Once they get to be about an inch or so, I move the ABN's to a 120 and the browns up to my 180. The 120 is also home to a couple dozen other fish and the 180 is my community tank up in the living room (which is in dire need of cleaning--dangit!). One day I'd like to have one of those really nice fish rooms where all the tanks are roughly the same size with a nice linear pump and a central water system. My fish room is a hodgepodge of various size tanks and stands. I've got a 120, 75, 65, two 55's, a 50 flat back hex, 30 long and three 20 highs running. And of course, I overflowed the R/O unit so I soaked the carpet and have had to rip half of it out... still need to fix that!
ah, the trials and tribulations of a fish nut!
regards
mike