Some tea questions, possible root rot or brown slime

I have 4 55 gal res's for my hydro setup (flo n gro). This is the first time in over 2 years I have had root rot but I seem to have it now somehow (res temps are 66-70 and have the largest air pump local hydro store sell with 4" hydrofarm air stones, makes ALOT of bubbles in my reses) I also changed recently from 6" grodans and perlite to hydroton as my medium and changed nutes from house and gardens to cyco line + aquashield.

How do people handle making a batch of tea large enough to handle this size reses? Should I get a brute container (holds like 44 gals) and just make a batch this large? I would need about 4 gallons of tea per res every 3 days, so make a new 40 gallons batch every week or something I would guess, how long will it be good for after the first initial 48 hours sitting at about 70 degrees? Just add more malasses every few days for food? Is this possible and ok to make batches this large? What would the cost be per batch?

Also what are some substitutes to ZHO powder? ill check in store when I go later but not sure they sell it. I do have some great white I purchased like 2 years ago that I never really used, can I use this instead of zho powder?

After reading some more I am not sure its root rot, its dark brown slimy looking stuff on some of my roots, my PH rises .2 - .5 each day in my reses requiring me to use ph down daily. root rot would cause ph to go down correct?

thanks all.

Pythium makes it go down, you're not at that point yet. The tea will help you for sure.

You're over thinking it. At first you want to add that much tea to get things on the right track. After a week you'll be adding 1/10 just to maintain the microbe balance. And it only lasts about a week so making 4gallons in a 5 gallon pale should do fine.

it'll be part of your routine now. Embrace it lol

just wait until you mess up a batch! That really sucks...

I have the tea made, in 48 hours when I add it to my res's can I have nutes in there or just ph'd ro water?

You CAN sure. But it's suggested to go water first with tea, then adding nutes 12hrs later. This will help the good microbes regain a foothold on the roots. I'd use this approach if i was trying to rebound some sick plants. Once under control and using just for maintenance, adding all together is fine.