I have about 20 ASF's...I have not bred them yet as they are still growing to breeding size....

I have to say, I keep them 1.3 or 1.4 in 10 gallon fish tanks...I go 2 weeks between cleanings and there is no smell..none....my problem is that they chew through water bottles all the time...I put 2x4 blocks in there and that slowed it down...
If I were you I would pick up the 1.5.....