He is talking about flushing for the purpose of reducing salts, not pre-harvest flushing. There is a difference. But yeah, some people flush for way too long.
Not true, Personal preference you can go as long as it takes to add back as much as the rez will hold before having to replace and then if you add back nutes along with the water you could go longer if you wanted you would just have to be careful and diligent with your math.
Ummm, you CAN do that but you are trying to prevent nutrient antagonism between different elements in your rez. Since there is no possible way to tell what nutrients are remaining in your rez solution, just adding back and adding back is a recipe for particular nutrients to get locked up. The kids new, lets not overload him. two week turnaround for veg and one week turn around for flower nutes. Top off rez with 1/4 strength nutes and tap water.
Oh and the H202 issue is Hot button as well. Look H202 has its place but if you are serious about Hydro Hydrozyme is the only way to go. Why fuck around with H202 all the time when you could just add Zyme and forget it? If you start using it out of the gate you never have any problems its when people don't and get into trouble and scream AHHHHHHH my plants have shit on the roots does everyone start on the H202 kick, Preventative maintenance people !! I never understood that.
People "fuck around" with h202 because it is cheap and effective that's why. Hygrozyme is a decent product and has its place but it is stupid fucking expensive AND it does not guarantee that your not going to have bacteria or fungus problems. You can induce "good soldiers" into your rez to fight off the "bad soldiers" or you can fuck that, add h202 and have no soldiers (and increase o2 amounts which is an awesome benefit. All this for about $5 a complete 3 month grow.
Again, this guy doesn't need to delve into the more complex and convuluded aspects of soil chemistry and microbiotics, he just needs to stop the plant abuse. h202...i.e. commercial grade hydrogen peroxide is available at any hydro store.