That is correct, synthetic fertilizers do not kill bennies. It is true salts are a sterilizer, but the concentration is not strong enough to kill bennies. Bennies are used in hydro for slime control, not to "break down fertilizers" although some of us do use nutes with organics (flora nova, pure blend pro, liquid karma, etc etc etc) and that absolutely does need bennies to convert the organic compounds. The slime control, which is the main reason for using bennies in hydro (instead of sterilzers like h2o2 bleach chlorine etc), works by inoculating the res with so many species of microbes that no one species can gain enough of a foothold to take over and dominate your res. Another control measure for slime is to use 100% 'synthetic' nutes so there are no organics to feed the slime. This starves the bad microbes, but also starves off the bennies, so we just simply dose with more bennies once or twice a week. This keeps the good shit coming in and the bad shit continuously dying out.
Enzymes will also help digest root bits and pieces of leaf that may get into the res. OP when you use bennies in your res it is important to not kill them with sterilizers like h2o2, bleach, or chlorine chloramine in your water. The chloramine is easy to deal with using a tap water conditioner for aquariums (API Tap Water Conditioner - Petsmart), but stay away from anything with slime colloids to help build fish slime coating. While you are at Petsmart or PetCo, check out the pond-zyme that is a good cheap product to use for bennies in a pinch. It contains bacteria and enzymes.
Heisenberg Tea has two recipes, one where he uses Aquashield + ZHO powder, and his improved recipe which I have used uses MycoGrow Soluble instead...
0ppm water - 2 gallons, but I make 3
a dash of MycoGrow Soluble from fungi.com or Great White can be used which is the same thing plus enzymes, mycogrow is much cheaper. Alternatively you could use Aquashield + ZHO
2 heaping handfuls General Hydroponics Alaskan Ancient Forest Humus - earth worm castings can be used instead which is where you get the term EWC tea.
1 - 2 TBSP unsulphured black strapped molasses I use botanicare. You have to be careful here not to use too much. The molasses is used to feed the bennies and should be consumed after 48 hours when you dump the tea into the res. Molasses directly in your res will damn near guarentee trigger a slime bloom.
I have tried the Heiseberg tea and I grow in DWC which is probably the system most prone to root rot and slime... and I have found just straight Aquashield with maybe a little pond-zyme to be the most effective at not only preventing but also curing slime. In other words, simply dump a few ml Aquashield in your tank once or twice a week and keep it below 70* and 100% light proof and oxygenated and you will be fine. For oxygen use either air pump and stone like for an aquarium, or put a water pump in the res so it is shooting a column of water straight up (this is called flooming). The water pump will likely raise your water temp a couple degrees compared to an air stone. For water temps insulation and light proofing you can wrap your res in a few layers (at least 3) of silver bubble wrap (Reflectix) from home depot or lowes.
