I really need to learn about dosing a macro tank. Any suggestions? I'm doing weekly water changes but I wonder if that will be sufficient long term.
You need to test and see, in a macro tank water changes alone may not do the job if you have a large amount. I would just keep testing and see when your nutrients are getting to low for growth. When you dose I would start off small and test to see how long it takes for them to be used up and you may need to raise the amount or lower it. Trial and error basically
Just as Josh says, it's all about testing your water to see what is needed to keep the parameters where you need them to be. I test the basics every week - calcium, alkalinity, pH and Nitrates. I never test nitrites, ammonia or phosphates. I test salinity every day or every other day, as that is the one parameter that scares me in small tanks - it just doesn't take much to push it out of range.
I have a lot of calcareous plants like Cymopolia barbata, Halimeda sp. and Flame Algae, so I'm having to dose calcium and alk buffer to keep them happy and promote coralline growth. To keep the green algae greener, I'm dosing a bit of iron every couple days. For overall plant growth, I dose nitrogen daily. I dose a drop of Lugols every other day for the Zoas, and I've also read that iodine (Lugols) helps the red macros.
It also depends on what all is in his tank, if he has alot of calcified coral or plants he may need to dose calcium, and also make sure your alkalinity doesn't get low. Does coral-vite cover the calcium? Im not familiar with it.
I dose Seachem vitamins and amino acids for the fish, coral and inverts. To be honest, I've not seen any difference using it or not. It's cheap and I trust that Seachem isn't going to sell snake oil, so if there is the potential that it will keep my animals healthy and happy for years to come (Chromis are supposed to live up to 15 years), then it's worth it to me.