Yea I know I go on about Venturis, Bernoulli and what not. Some of this stuff is not used as of yet but will be or is for other apps. I'm super OCD and tend to get fixated on things. I'm just really passionate about it because its provided me with a lot of material to use.

If you do use a Venturi injector, try an oxidizer like hydrogen peroxide on a weekly basis straight into the solution at about 1/2 to 1 teaspoon per gallon, then proceed with greater circulation you should eliminate a lot of this dead organic material that tends to fester. If your using a top feed or drip make sure everything can breath, theres no dead spots. I had major issues with root rot during my trials with aquaponics so I understand the frusteration. My experience has been in reguards to root rot that oxidizers and circulation will be your best route and to take steps above and beyond for piece of mind I would even flush 2x with chlorinated water that is ph adjusted, just to get that sulfur, gas, and organic matter out- leave the chlorine in until it wicks off.

good luck