I originally built the stands just to hold tanks. My end plan was to incorporate lighting & a drainage system for general drainage of old water for cleaning & water changes & to be ready for a centralised filtration system should I decide to do this in the future. For killies a flow through system is not usually a good idea but I also keep livebearers which do approve of flowing water. The new stand could accomodate either.
I'm no millionaire so fish had to be bred to fund this project.
I started modernising my small breeding tank stand by striping all the tanks & putting them back into my old fish house. New tanks needed to be built at 40 x 40 x 25cm high. Basically a 16" square tank 10" high. The base was drilled in the centre for the tank connector to fit.
The cost of modernising this stand with lighting, drainage & new tanks was around £500. A small business had to be set up to fund this where fish, foods & brine shrimp were sold to enable this work to go ahead.
The next 2 stands will cost over £1000 so more fish will need to be bred & sold to fund it. This will put the cost of the fish house up to £6000.

View down the length of the modernised stand with the first tank in place. Note drainage channel to left & lighting to right. A 16" wide stand is tight to cram all this in & I would recommend 18" to be comfortable.

Another view at a side angle.Plenty of space is available for return flow pipes & air blower pipes.

View showing underside of top row.

End of row drainage column which joins up with the other rows. Leave the top of this column open to speed up drainage.
A 1" layer of the insulation had to be removed to accomodate the downpipe but that still leaves 3" of polystyrene at this small point.

Tank base showing drainage point. The 2nd screw fitting from the bottom detaches the upright pipe for drainage. Another pipe can be fitted with a gauze for a 30/50/75% water change. Just fit it & let nature do its job.
Note angled tank connector with a 4"waste pipe fitted. This channels the rush of water into a jet directed down the waste channel & not onto the striplights.