Maracyn plus 2 is for gram negative bacterial infections, not positive gram. This is why Mardel claims it will not interfere with your biological filtration as your biological filtration is mostly composed of gram positive.
TC is Tetracycline which is an "old school" gram negative anti bacterial med. Its been around a long time. Some say it is ineffective because its been used so much, bacteria has grown immune to it. Maracyn 2 is a better choice.
Blanket treatment? Do you suspect bacterial infection? IMO these meds should be used as a last resort. These are powerful meds and can at times make things worst.
Yes, these meds do expire. There will be an expiration date on the packets or box.
Well I had some outbreak a while back that was basically incurable(lost over half of my fish across many tanks and different systems it jumped on the siphon hose) but I comboed maracyn 1 &2 with solar salt and got through it. I aquired a ton of fish from this guy and they all had what I thought was worms but I'm treated them for that and they have passed it but are still getting sick with non descript illness.
