check rotifers under microscope ?
 

Hello reefers
i have some rotifers I was wondering if anyone locally have a good microscope to take a pic if the rotifers are still live or dead ?

You should be able to see the rotifer masses moving if you have a strong light source to direct at the container. The rotifers will slowly gravitate to the light.

You can also see rotifers fairly well using a Jeweler's Loupe which you should be able to find for $5-10. Also, dead rotifers sink when there is no water movement, so if you scoop out a shot glass from the culture and put it on the counter for 5 mins, if there are any alive you will see them in the water column as long as your eyes are decent (use reading glasses if you normally use them).

I got a old microscope from a buddy but i cant see anything , when i put food in there after few hours the water goes back to yellow

If they are dead the water won't clear. ;)

When I first started to use my microscope to look at rotifers, it took me a while to realize I was using too high a power. Try the lowest magnification first, remembering a tiny movement of the sample up or down can mean going right on by the viewing as it can be very sensitive to adjust.
Also, sometimes if density of the rotifers is not high, then the sample drop may not actually have one or more rotifers in it.