I have never used the ASM, only the true Euroreef. I like the Euroreefs, I will personally always use Tunze though because they are more enery efficient and I completely understand how to tweek and tune them, they run very consistently for me and the skimmer cup has two features I really like- when it is full skimming stops and you just lift it up to remove it, no friction fit, no flange, no union. On the downside, without a constant waterlevel you won't be satisfied. The ASM could likely skim a bit better if properly tuned. I don't know though, I hear from customers who tell me there 240/3 beat there ETSS, I find that ahrd to believe but I think alot of it depends on the chemistry of the water and some of the studies we undertook at Tunze several years ago showed some interesting results in what different skimmers removed and the designs did effect type of material removed quite a bit. So it is possible that one would out perform another on a certain system and then seem rather lackluster on another.