Tank is plenty large enough. What is your refugium setup?
In terms of adding pods - once your tank is up and running (you’d is) you should only need to add each type of pod once, adding to the refugium. Either they’ll colonize or they won’t. If they don’t it’s likely because the tank isn’t suited to them (too warm, for example) and they won’t colonize no matter how many you add. If you’ve added inverts (snails, crabs, etc) you’ve almost certainly got random wild pods in there too.
If you’re going to add any more bottle pods add Tisbe, which typically colonize reef tanks well and are a good size for the mandarin while being too small to interest many other pod eaters.
All the pods you list though are tiny. The only way you’ll see them in your tank is at night and if you turn your power heads off, turn your lights off, turn your room lights off then wait about 10-15 mins. Then in the dark use a small flashlight to light up a pane from the side with your light pressed against the glass. Look at the glass from around the corner - this will light up the pods on the glass without the light drowning out your vision. You should see tiny specks moving around on the glass.
Alternatively, although this is less effective, send a flashlight beam through the tank, then very carefully look at it from the side. In the still water you’ll see tiny flecks swimming around.
With the power heads and so on on there’s just too much movement a lot of the time to separate out the pods from everything else sloshing around in there.
