I would only brew it for 18-48 hours under heavy aeration (like the jets in a spa). After about 36 hours the beneficial organisms use most of the food and need more (fish hydrolysate, or whatever you use) or will die. As far as using it you would need to keep the tea aerated and keep adding food for the microorganisms to keep them alive. Can probably find out more by looking up the soil food web even though you are using it in a DWC system. Just for fun heres my compost tea recipe: Alaska humus- 1C / gal , worm castings- 1/4 C / gal , bat guano 1-2 TBS / gal , liquid kelp- 1 TBS / gal, fish hydrolysate- 1 TBS / gal, liquid humic acid- 1TBS/ gal. Dry stuff in a pillow sack or compost tea bag and liquids in the aerated water. I use this for watering or 1/2 Str for foliage sprays. My friend said to add yucca extract for the foliage spray to get it to stick to the leaves better, so I might add the yucca... Ok i just went off. GL
-bts420