PMDD Pre-Mix question! :D

Hmmmm.....can't comment on dosing once for a whole week. I use both and it's an almost every day thing.

The thing is that your plants are going to suck up the nutrients pretty fast and really need to have them available each day. If you overdose them at the start of the week there will not be enough at the end of the week. The rollercoaster of fert levels will not be good for your plants. You might be able to get away with dosing for 2 days at a time.

I dose with the feedings (if they fish dont get fed, neither do the plants). For my 72g lightly planted I do 10-15 ml per day.

at this point this question simply cannot be answered. there's a lot of details that go into a single tank... and 2 identical tanks treated identically side by side already will likely have different outcomes/preferences. not knowing what's in the tank (specific plants, fish, inverts, etc.), what's all going in the tank (w/c's, ferts, root tabs, foods, etc.), the size of the tank and your water chemistry, lighting, filtration, etc. are simply compounding the issue.

at this point i see no source of ca, P or co2. not that your tank necessarily needs it, but it's my opinion that it's best to start by providing everything and eliminate what you don't need one by one... or run extensive tests to determine what's low.

with the pmdd, i personally would be adding plenty and doing w/c's to keep the concentration in the tank in check. mind you... "plenty" will differ from tank to tank. the idea is not to have too little of anything. think of it this way... thanksgiving dinner... in a paupers house there may not be enough food to go around and the deficiencies would show on the pauper. at most thanksgiving tables there's too much to eat... which is fine because we can simply choose not to eat any more than we need or want. the same goes for feeding your plants.... if the food is there they'll eat what they need... if it's not there they'll suffer. the benefit when it comes to a pre-mix pmdd... if your plants still suffer you'll know it's something else you're lacking (most likely listed above). simply add it in a schedule for a few weeks and see how things go at that point. not enough?... didn't do the job?... plants not recovering?... add the next thing to your routine. once your plants are doing well you can start throttling back on your ferts one at a time and possibly eliminate one or more from your routine... unless you're running carbon also.

HTH
take it easy.