If you have a coffee grinder you could use, you can try grinding either pellets or flakes super fine.. you're looking for something that resembles baby powder in consistency.
Green water is an excellent food for filter feeding shrimp and it will not give your tank an algae bloom. But blending or otherwise processing other types of algae may well result in a tankful of algae.
If you want to, you can culture green water, either by starting with tank water and leaving it in the sun, or a sunny window, or under lights about 18 hour or more a day.. or you can buy a single cell algae culture and grow that. The advantage to the pure cultures is you know just what you're putting in the tank. I used to shoot about 100 CCs of this twice a day into a 5G tank to feed larval shrimp, it never caused problems. Only a sponge filter in there too.
I find the best way to feed them is to turn the filter off for an hour or so after their food goes in. I have a separate pump running in the tank that provides current even when the filter is off. This keeps food circulating for longer so they can get more of it.
Other foods that are useful are; Powdered spirulina [ shake some in a sealed jar with water and pour into tank].. Golden Pearls, 5-50 micron size.. ideal for filter feeders. Made to replace BBS actually. Frozen BBS also work.
If you are willing and can get some, culture micro worms. These are ideal food for filter feeding shrimps, and fish love them too. Even cherry shrimp eat these.
New Life Spectrum makes a fine food, Small Fry Starter.. it also works for filter feeders, but I would not feed it every day. Be careful not to use too much of any dry food, they can clog up filters if you overdo it.
Most important, a good strong current and perches so they can sit in it and feed. You do get the odd individual that is more of a bottom scrounger, but usually they don't keep it up for too long. So long as you're seeing poop on a regular basis, he's eating.