Aquabus works only with Aquaero controllers. The Octo can act as an extension to Aquaero, but the Octo can't control devices through Aquabus. It's better to use USB for both

Why two controllers ? One Octo is more than capable to run all your fans even on separate loops. But either way, Aquasuite will pickup both Octos. You can even add a description to both to easily differentiate them, and they don't get mixed at random like iCUE does :p

Few people hate Corsair and icue more than I do. Their controllers are cheap plastic junk that are not able to run autonomously. Their USB ports have constant drop out problems. Their RGB fan and AIO wiring methods are dated and overly complicated. They don't use the proper global mutex's to poll system sensors, and icue itself is a bloated, buggy mess. I gave up on Corsair Link/icue and Asus Aura and Armoury Crate a long time ago. That said, there are some things that I can do in icue that I have not been able to replicate in Aquasuite, but those things are not worth installing icue. Aquacomputer RGBpx is a great platform but I have found it difficult to figure out what some of the adjustable settings actually do, and how to use them to attain a desired custom effect. I also wish that they would add a basic Marquee effect which is available in icue and OpenRGB. I have tried to make a Marquee effect in Aquasuite but have yet to figure out how to do it.

2 Octo's - Remayz is spot on. You can absolutely connect more than one Octo at a time via USB. You would only use Aquabus if you were slaving an Octo to an Aquaero. I also agree that one Octo can control all of your rad fans, assuming you are going to run all fans on the same rad at the same speed. Individual speed control of fans on the same rad is really not necessary. Just link all the fans on each rad together with a PWM splitter and drive the splitter from an Octo port. Just make sure you do not exceed the 2 amp current capacity of a port and 8 amps total for the Octo. Also, be careful if you have QL series fans. They have 34 LEDs and the limit for an RGBpx port is 90 LEDs, so you can only connect 2 QL series fans per RGBpx port. The Splitty4 is made to connect 4 Corsair RGB fans to and RGBpx port but for QL series fans the limit is 2.

you can use splitty 9 Active for the fans PWM if using splitter cables overload the Octo. they can drive 9 fans each and use sata power. https://shop.aquacomputer.de/product_inf…roducts_id=3830

one for each big rad would do great, then you can use a normal splitter cable for the small rad. in the end you'd have lots of spare outputs on the controller

The Corsair ML Fans only have 4 LEDs each. 16 Fans with 4 LEDs each is 64 LEDs total.
You can daisychain the Splitty4s, and connect all Fans to a single RGBpx Port on the OCTO.

And you can use Y-Cables for your Fans, and connect 2 (or more) Fans together on a single Fan output on the OCTO.

One OCTO is enough for your configuration.