Good write up.
After years of side by side testing, and always looking for what works for me(a simple home grower who smokes an oz a week), and is the simplest, cheapest, and most effective. I've come up with a couple of things I'd add.
1. In addition to Hydroguard, Flying Skull's additive Z7 is a must. It's worth it just for how much cleaner my buckets are staying and I only use 2ml in each bucket on weekly water change days. When my season begins again next Sept I am going to run buckets with just the Z7 to see if I can do away with the Hydroguard. I've heard of people doing this successfully and if it works that's more $$ in my pocket.
2. Chasing pH is a PITA. Especially in 5 gallon buckets when your actual nutrient solution volume is more like 4 gallons. Do yourself a favor and spend a little more for Advanced Nutrients pH Perfect 3 part, and never bother with checking pH again.
Regarding the pH Perfect......I tested this many times, even went 18 months without a pH pen. It works. And it works at much lower dosage than they recommend. I average 5oz per plant in 90 days and never use more than 21ml/4gal. AN says to use 60ml/4gal.
At lower dosages using tap water the pH going into the reservoir will be between 6.1 and 6.3 No worries, the chelation factor still allows for proper uptake. HOWEVER...for this to work like that, I always adjust my top off water to a pH of 6.0 , and change my reservoir every 7 days or sooner. If a plant has used 14-16qts since the last water change and the week isn't up yet...change the water! Don't wait for the regular day. This is where note taking is important.
That's my $0.02
DWC can be a very easy way to grow huge harvests . Just don't over think it.