I've seen food grade buckets at both home depot and walmart but they can be harder to find in black. I have some white ones I use for ice water hash. Hydroguard is a bacterial based root zone innoculate. It's a voracious bacteria that eats up dead material off the roots keeping them clean and hopefully outbreeding the bad growth. Plenty of air also helps keep bag growth in the res at bay. I would say between 100-200 gph per bucket. I use more then most people. With larger thicker root balls I was at one time having some bad growth issues. Fixed them all by adding a second stone and air line not some magic supplement. I watched them bounce right back to white healthy roots from just doubling the air. Two basic approaches to DWC bucket growing. Either supplement the root zone with your own microbes or sterilize it. If you do neither you'll likely eventually deal with bad root growth. Along with hydroguard I would recommend a fungal microbe root zone supplement as well. That's why GH's rapid start is a good product. It has both bacteria and fungus in one bottle along with a few other additives. Another few root zone products that have about 4-5 classes of supplements in them are Great White or Real Grower's Recharge.
The "sterilize it" Tbone mentions can be cheaply accomplished with clorox. I add 2 drops per gallon per day, and have never had root problems.
Without a chiller, Hydroguard is a must IMO. I use a chiller and still supplement with Hydroguard... Good luck....
I'd like to help. Been growing some plants in hydro for a few years. I have found two primary offenders for hydroponics and it's microbiological. Algae, and micro-organisms who feed off the nutrients and deposit base acids that benefit the algae. These bugs have three primary growth necessities. Light, Heat, and PH. Additionally, They can also change the PH of the afflicted water that sometimes rises to the top if the Bacteria/fungal brood becomes too powerful. Creating a 4.0 and lower PH zone at the skim of the water, which can expand to the rest. Heat opens the door for micro-organisms to multiply in abundance. Light opens the door for algae to grow in abundance, PH water is the medium in which they survive. They could not survive a 14 or 0 PH, then again, neither could our plants. Keep in mind too that none of the water is sterile, Root symbiotic Bacteria will thrive and survive in the root zone, increasing the bio-availability of nutrients to the plant, Just like our gut flora do for us. 7 Facts That Will Make You Rethink the "Sterility" of Hydroponics The algae and mold and the most dangerous factors. Both jump on the roots and siphon nutrient intake parasitically. If you have rainbow water at the top it's in the beginning stages of the takeover. (Fun Science!) You have to be careful with the heat. L.A. has some pretty hot days and beyond 105 with direct sunlight the plant itself will suffer level 3 heat exhaustion. Too many days like that and it won't survive. The water is not insulated the way soil or coco would be. So you water will match resonating temperatures. If its 105 outside, your water in your root zone will be 105 too and your plant would not be happy, depending on the breed it may not handle it at all. (Indica, South america, Cold, Close buds, Tighter formation to insulate) (Sativa, Middle east, Hot, longer stems and aerated buds, to allow breezed cooling.) Your plant looks like an Indica to me. So here are my suggestions, one air pump, one air stone, and one 7 dollar recirculating pump with a hose that leads to the top of the bucket while still yet under the lid, should Diminish the capacity for microbiological growth, These bugs need static water, The more you move it the harder it is for them to multiply, The hotter it is, the faster you may want to consider moving it. You may be able to negate some temperature and most light by wrapping that bucket in a black towel, or burying the bucket 90% into the soil. Maybe even some actual insulation wrap, The kind they use on your incoming water pipe at the side of the house. If you keep the water cool enough or moving fast enough, those organisms have a tough time breeding. Keep some hydrogen peroxide on hand, this water is exposed to the elements and will Occasionally interface with pollens, and molds, and fungal spores that fall from the sky, HP in a spray bottle does a great job an eliminating a lot of them. Those are my best suggestions. Let us know how it goes in a few months too!
Looking good. Nice mylar bubble wrap. That would have been my choice too since it insulates as well as reflects. Cut a circle with a slit in it and a hole for the stem and put it on the top. You probably still are getting blue light through the lid in the res. Roots like dark.