Here's my 3.7 gallon shroom tank. It didn't start out as a shroom tank haha. There's a nice little m/m carpet nem, a neon toadstool in the back, and a electric green shroom that's being tormented by the red shrooms sadly.
Inverts are a pair of sexy shrimp, a nassarius, trochus, some asterina, couple small hermits, couple small ceriths, and a healthy pod pop.
I've got a couple small limpets that I've just noticed recently, tank has been up a year.
Equipment is 50 watt controllable heater, reef glass skimmer, ato lite, kessil 80, and a syncra return pump.
I run nano packets of chemipure blue and dose MB7 at water changes. I change a gallon a week. Top off is about a pint to pint and a half per week.
I feed LRS or frozen mysis once or twice a week, mostly to the nem and the leftovers feed the rest of the tank. I lightly feed phyto and plankton on alternating days once or twice a week. The occasional shrimp pellet here and there. It's way easy to degrade the water quality if you aren't judicious with your feeding.
I enjoy this little tank on the days I work from home.