Hey!
I am new to this forum, but not to Hydroponics. I have grown peppers indoors, and out.
I have not ever had to swap out my reservoir to be honest unless there was an issue. As noted above, unless it stinks, or you want to be extra careful. You can, it is just an added cost, and time. I have grown using many different methodologies. You can have stinky hydro that is fine, and odorless. Depends on what all you are adding. Add too much Myco, and you gum up the entire system, and in a week it you will be changing it. This is super true if you are doing it indoors. Now, this is based upon my experiences. Depending on what nutrients you are adding, their schedule, etc. you may have a different outcome. If you are attempting to go down the "organic" route, then this could change it as well. Some smell will come from that (I know). Slime in a typical hydro setup (usual grow + bloom nutrients, nothing fancy) then that is a serious sign of a true issue. Do not just change the water, remove the water, thoroughly clean the reservoir, purge anything that the roots are in. You can do a diluted bleach on the reservoir and water. For the other stuff, H2O2 does wonders cleaning stuff, while not harming the plants.
Peppers are easiest in my opinion outdoors. No lights to buy, no expensive electricity bill from the said lights. Plus, instead of swapping out the res, I found that when it rains, it usually overfills the res. Then you just have to check it after a rain. In the heat of the summer, you may find that you have to check your res once a week to ensure it has the right EC/PPM/pH, etc. Once you do that, mostly I top it up with fresh water once a week, and may add more nutrients every other week, sometimes even once every three weeks. Just make sure to keep an eye on your res level.
I used to use those 27 HDX totes for a res. Those work great, and last several years even outdoors. Keep it shaded outside, or keep it away from animals indoors. I moved on to using 55 Gallon drums. The more you have the less fuss you have with it. That was the real reason.
As for the other question regarding how many plants per 27 gallon tote, I honestly would not do more than 16. Outdoors I utilize a top drip method (I made rings around each plant with a bunch of holes in the rings). I dripped 3-4 times a day, plant size, and time of year dependent.
Indoors, 1-2 a day was fine for drips in a more controlled environment. Typically you can go heavier on the nutrients indoors as well. Outdoors, they get thirsty in which they want more water in higher heats, and less nutrients.
Keep an eye on it, test ECC/PPM + pH once a week. Look at the leaves, look for any discoloration. Look for any leaves rolling up, or down. Do not get crazy with it. But things like leaves turning color can mean nutrient deficiency, or over watering, etc.
If I left something unanswered, or if you need anything else, do not hesitate. :-)
