I wasn't trying to take pictures of the growing media when I took the pictures, so you cant see it real well in some of the pictures. But all the plants in these pictures are growing in coco chips.
Mildew is caused by fungus, not water. Moisture only allows the spores (fungal
seeds) to germinate and grow (like any plant). Spores can be in the water supply, air, even anything you touch that isn't sterilized can transfer spores. So it dosen't really matter what growing media it is, it's still going to be susceptible to fungal spores (and thus mildew). If you let the growing media dry out (to kill the fungus) you'll kill the roots as well. Without moisture in the growing media (24/7), the plants will die regardless of the growing media used.
However if you allow light to get to anything that is wet (with the
nutrient solution), algae will grow. But again that's true for any growing media, even clear tubes and other things than the growing media. If it has moisture,
nutrients, and light, algae has all it needs to grow. So just keep it from getting any light, and it wont grow algae. Mildew and algae are two different things, mildew is a fungus and dosen't need light to grow, algae does. Right now I am not sure if algae is spread by spores or not, i would need to look up how it reproduces. But fungus (mildew) grows without light, and is spread through spores, but algae simply needs light to grow no mater what.
Usually in a flood and drain system the water level is about 2 inches below the top of the growing media. Because of that the very top of the growing media is dry, and the moisture is below it (where it dosen't get any light). So then algae dosen't grow. With the broccoli plants (the plants in the large 5 gallon buckets), I made it a
drip system with the drip ring on the very top of the growing media. So the top of the growing media definitely grew algae. However that was easily remedied by itself when the plants foliage got large enough to block the light from the top of the growing media. Then the algae just died and diapered. I could have also added about 2 more inches of coco coir to bury the drip ring below the top surface. That would also block the light from getting to the moisture.
P.S.
I was able to fill the four 5 gallon buckets with one 2 cubic foot block of the coco chips. I filled the bottom of the buckets about 1/3 of the way with cleaned and sanitized rock. The rock provides weight so they wouldn't blow over in the wind, also the rock at the bottom prides excellent drainage in the containers, and takes up space so I could fill 4 buckets instead of only three. So essentially each 5 gallon bucket is using about $2.50 worth of growing media.