i wouldnt buy live plankton. the problem is if its not refrigerated it goes from a useable micron size to too big for usefullness really quick. on dday who knows, the feedback may be great but the people buying it arent measuring micron size. thats what counts when it comes to plankton. they are giving feedback on dealing with the other person. as far as phyto plankton goes if some one mailed it to me on a warm day, if wasnt sent in a refrigerated truck i would dump it down the drain before putting it in my tank.