Ive also read that u can use spectro and GC together. Does that mean i can use all 3 concurrently?
You can, certainly. Mixing meds has it's disadvantages/risks, however. One of them is algae blooms (spectrogram will actually not allow this to happen), another is reduced oxygen levels in the tank (bubblers AND powerhead breaking the surface are advised), and another is weakening a fish due to the chemicals/medication combinations -- more meds increases this risk and also can reduce the immune response of the fish. In some cases, it is a necessary evil -- but unless you see a need to do all at once, I wouldn't.
I've brought several batches through recently by just mixing copper, metroplex (for uronema) for 14 days - then transferring to an entirely new, sterile quarantine that shares nothing with the first for prazipro. I feed general cure and focus generally for 2 weeks in-between transfers --- in other words the second week in the first QT and the first week in the new observation QT. I also treat with prazi pro at 1.25% normal dosage 5-7 days apart during observation as well. I haven't been seeing much flukes recently, but if i saw scratching or flashing or evidence of them in the first 14 days I WOULD combine them. In the absence of such, I wait to for the aforementioned reasons.
I've also switched to CP because I've had two failed Copper batches. Full disclosure -- I used 2.25-2.5PPM both times HOWEVER I have been sloppy and multi-tasking so it's possible both failed attempts were cross-contamination with food, hands in tanks, drain hoses, and a myriad of other ways. I am unsure if velvet survived copper or if it was user error. It did happen twice in a row so I've moved to CP recently with good success. CP is difficult to get right now, obviously, but I had a bit left over. I am still pretty confident in Copper Power at 2-2.5PPM, but it is POSSIBLE perhaps that velvet is surviving even higher concentrations of copper. I am unsure.
Because of my working from home, being a kindergarten teacher to my 6 year old daughter, a daycare for my 4 year old son, and a massive uptick in business for me with all of this coranavirus stuff, I am stretched very thin and when I try to multi-task (talk to clients while working in fish room) I have caught myself making silly errors I wouldn't under less pressure and under normal circumstances. In short, I am stretched very thin.
Does general cure work with the powder form vs medicated food form
General cure in powder form is typically used for both. I add it to food, with seachem focus, and mix up with a touch of garlic to improve flavor to make it more "palatable". For dosing in the tank, I also use powder form. The only liquid form medications I use are Prazipro (prazi is one of two main ingredients in general cure, the other is metroplex) and Copper Power.