Good point! I dosed according to what seem to be agreed upon internet instructions since there were no directions in English on the Planaria Zero and only by weight of a canine on the Fenben. I am dosing these estimating that there is 9 gallons of water volume on tanks 1 &2, and 40 gallons on tank #3 (which isn't really part of this comparison).
Tank one: Neocaridina davidi
(black rose color), Caridina cantonensis
Dosed with 1.5 grams Planaria Zero initial dose, 1.5 grams after 24 hours.
Tank two: Neocaridina davidi
(goldenback yellow color), Caridina cf. cantonensis
sp. 'Blue Tiger' (orange eyed royal blue tiger)
Dosed with .1 gram of 22.2% Fenbendazole, premixed into RO water. I remembered from last time that this stuff does not dissolve easily. Dosed same amount after 24 hours. I had read both 24 and 48 hours for the 2nd dose and decided to just do them on the same schedule.
Tank three: Neocaridina davidi
(blue dream color), Caridina multidentata
Dosed 4 grams of Planaria Zero, deliberately underdosing as I'd read that a 50% dose was effective for many tanks and I didn't want to disturb this one more than I had to with injected CO2 on top of medicating.
Day 3 (early) update.
I can see a few worms in tank #1 but they seem very unhappy. None are above the substrate line nor moving much.
I cannot find a single planarian. That's not to say that there aren't any, but the one that was on the glass yesterday is a white stain at this point. I tend to think that Fen Ben is faster-working, though that's not indicative of being more effective long-term, nor safer for fauna.
Is a 45 gallon with Eco Complete inert substrate. Still active planaria in this one. Perhaps I shouldn't have underdosed and it will receive a full dose tonight.