I'de ditch the tiger barbs, common pleco, clown loaches. and thats just to start tbh.. Tiger barbs are nasty mean, particularly in small groups and in small tanks. I've seen them busting 3" + and they will likely destroy everything else in the tank eventually. common plecos.. while you pond may need one... put it into you pond... the bio-load and fast growing nature of these fish not to mention their aggression potential would just spell trouble. water quality will get shot to heck, and your likely to lose a small fish or 2. Clown loaches do grow slow, but need suitable size groups. people will debate this.. imo/ime a group of 6+ does best. And they are notorious for illness, and being "hard keepers".. with the bio-load your intending on such a system. simply put. more likely then not your gonna throw a good amount of money down the drain on these fish.
I am not trying to be overly criticle but simple honest with you. like I said thats a start.. those are the 3 red lights I see.. and the whys.