Im seeing a lot of bad advice here.
For one cyanobacteria and any root suffocating mucuses don't care about ph or ppm, or DO for that matter. It's a temperature thing. So a chiller will help there, but you still want hydro guard (aquashield) to keep your res clean. This is called running a live res.
Next SS's advice with the pondzyme is accurate if you're fine growing "adequate" plants. By his picture intended to credit his advice we can see healthy plants growing. They are by no means thriving. I look to see no pale leaves and all tips pointing to light source (praying). No offense to superstoner but the only way to accomplish this (in my exp) is with nice pearly white roots, (which i anyway) can only obtain by brewing an AACT.
And lastly, i'm not saying brewing it is easier than scooping some powder into your res, but it ain't rocket science! Takes 5 minutes to start a batch, 5 minutes to finish one (48hrs later). I brew 1 batch per week and keep a 4L jug of it in the fridge for halfway through the week. My plants thrive even at 80f res temp. And $30 worth of tea ingredients lasts a year +.
Oh ya and ps. Add as much as you want it can't hurt the plants. It also doesn't use any more DO once brewed, so it won't deplete your DO any faster than without as stated somewhere above.
