Ross,
There are all kinds of "recommendations" out there.1 gram per 20 gals is 500 mg per 10gals. The generally accepted dose is 250-500 mg per 10 gals. Some dose it every 8 hours which doesnt make sense to me... from previous discussions here its based on extrapolated data from non-aquarium conditions. Some also jack.up the temp for similar extropolated reasons... 84 F is fine,Imo.
Your metroplex contains 70% metronidazole... you need to use more to compensate
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500 MG/10 GALS 7- 10 DAYS.. Large water changes before dosing . This is an effective treat many discus keepers here use.
What are you treating? The above info I just posted is for hexamita/spiro.
Al