I use 5g water bottles to grow rotifers, and 26g rubbermaid garbage pails to raise the brine shrimp.
Those reactors would never supply me with enough product to feed my production of rots and brine so I used 5 and 6g pails and 26g rubbermaids to supply enough.
Now, I just have a couple of gallons of nanno that I use for seahorse fry containers when I have any on the go.
For the amount you are using, Jason, the phytoplex should do just fine.
For me, it would be EXTREMELY costly.

phyto
 

the problem with phytoplex is that the cells are dead.i like to culture my own as it is live

Live or dead, as long as the nutrition is right and the rots and brine feed on it, it works for me.
It saves a lot of extra work to culture the live, especially when multiple types are needed.

Do mandarins eat roti?

That I don't know. But mandarins eating brine is a crap-shoot also. Some will eat brine while others don't. Rots and brine are not a natural food for them.
In any case, the rots are so small it would take an awful lot of them to be of any significant nutrition input.
A lot of corals feed on rotifers.

What's a good and easy way of feeding my mandarin? Since I can't find any1 with pods in the area and JL sell them at rip off prices

pods
 

there are many people with pods in their sumps.some filter floss in anyone's sump could get a starter culture of pods.rotifers can enrich brine shrimp for feeding as they are microscopic,but they are only as nutritious as their last meal.that's why i feed my rotifers various phyto.also check with anybody that has filter socks.you could get pods from there as well

Rotifers are too large to feed to brine nauplii. Brine nauplii are looking for food in the up to 50 micron range whereas L strain rotifers run 200 to 350 micron range.
Even if you could find the S strain, they run at 150 and up.
Try the brine nauplii first to see if it will take them. You will almost certainly have to turn off the sump return pump, and anything else that will damage them or blow them around. You can put a light source at the bottom of the tank to see if they will gather there for the mandarin to find and feed on.
It's possible sometimes that a mandarin will only go for the brine in a particular size range so you may have to grow them out to a bit larger size.
Full sized ones haven't appeared to be of any interest to the mandarin I had, but juveniles were accepted.
For this trial stage, you don't have to bother with the enrichment because all you want to do is find out if it will be seen as food.
If so, then you can follow up with enriched nauplii.
You probably have mysid shrimp in your tank so putting a pile of small rubble on the tank bottom will help to provide higher mysid density.

Last night I noticed the first trail 2 turkey bladders of live baby brine that I squirted into my chaeto and DT were floating around in my DT dead.

Might have been a question to ask before you got the mandarin.