You breeder is crazy! I've had discus for a while now and they seem to love my tank and it's not a bbt.
The only good thing about bbt is the fact that it's a snap to clean. You don't have to worry about picking up sand you just suck everything out.
Oh and the discus won't have a place to hide so you could see them all day long
But then again thats probably not very cool for them. It's kinda like throwing you in a scary place with no cover. Idk If other ppl agree but I love my little guys and think that's messed up. My hearts just kicking in a guess...anyways
Now if you have a planted tank that makes it a little harder cause you can't see all the poop and food. But if your not lazy and suction good along with weekly h2o changes you will be good. You still won't get everything but hey thats what a filter is for. So just don't cheap out on a filter make sure there's good filtration without to much water disturbance. As you probably know discus don't like fast moving water.
Another plus to a planted tank is the fact that plants will soak up some of the toxic waste that poisons the fish. It's like natural filter in your tank!
Plus it really makes your tank stand out and look good!
In the end you could go either way the decision is yours. The difference between a planted and a bbt will not kill or harm your fishes.
Good luck hope you enjoy those little guys!!
