Agree with all you said. I used AC over 20 years. Long term issues with them have been: 1. they are not self priming, and often do not restart when the electric goes out. 2. The joint where the two intake pipes connect, always clog in a few weeks, even with a sponge over the lower intake. A newer issue is that when they were bought out a few years ago by Hagen they lost their quality and durability. Impellers in particular are now junk and the plastic, while see through, is cheap and easily cracked. Coupled with the fact that Hagen’s customer service is horrible makes them unusable for those of us who used the original product. Tidal is self priming, never clogs as its one piece intake, and has a huge media basket. Customer service is great as well. I ran half Tidals and half AC for about two years. Most of the AC had broken or burned out the impeller by then. I run two OLD AC now and the rest Tidals on 60 tanks, fresh and salt. It will work well due to the design for a time but the substandard parts and materials will begin all too soon. Sharing my experience and that of many others. The Tidal cost a couple bucks more but it’s dependable and reliable - a real workhorse.

Do you think this filter is quiet enough to sleep with in the room?

That 40 is technically a 38.4 isn't it?. I have what I think to be that same tank I just hooked an aqua clear 500 on. I had to get new foam and a bag of carbonate. I'm not using it for breeding though but community fish.

Yes fill it with sponge! It's super inexpensive and the best media you can use. People don't realize how worthless ceramic media is.

The self priming filters aren't self priming, either. If the water level is at the same level that is too low for one filter to prime, the other won't restart. I absolutely love aquaclears, and you get a lot for minimal compromise. Far better than those dreadful Tidal filters.

that's a huge ass koi

Ugly terrible set up