https://www.rollitup.org/hydroponics-aeroponics/327967-bleach-instead-h2o2.html
My situation was never as bad as yours but an aquarium chiller and h202 did not solve my problems, only suppressed it for a while.
Bleach is normal in your local water. read the thread above. It saved my plants. If you would like to see what my plants look like after a dose of bleach them check the thread in my sig. (last post)
All you need is bleach @ 2ppm for an initial dose which is what is in the water anyways then drop down to .5 constant. Some chem ferts have chlorine added into the solution. Its been used by commercial hydroponic greenhouses over 4ppm for years.
If you use organics you must use bennies. Since bennies colonize the root zone of the plant having a detached reservoir like an ebb and flow is hard to grow in. Having a system like a drip feed where the nutrients drip through a rockwool slab acts as a natural bio filter so then bennies can have a large area to kill the bad shit. WHen I started using organics in my ebb and flow, the plants seemed okay because the bennies were at the roots but could not thrive in the reservoir.
Peace