OK Bill!!!!!
I would recomend these three "additives" as you requested. Forgive me if they are not all available in a bottle......

A good pH monitor. Mine is an American Marine Inc. Pinpoint pH Monitor. It totally takes the hassle and guesswork out of pH fluctuation. I found it under a google search for like $90. I've had a digital pH pen, test strips, droplet style, you name it. One of the best investments I made. You can actually watch your pH change live because it measures it to the 100th of a degree like 5.83. You can lose days of growth due to the wrong pH levels. You can grow big plants in 72 days with the correct environmental conditions.

Airstones!!!! Have lots of good aeration in your reservoir and use at least a gallon or two of nutrient to each plant (two being better). These rules allow for a more stable pH and TDS level.

Floralicous Plus by GH. Contains beneficial microbes and kelp extracts, the stuff you want. You use only 1 teaspoon (5 ml) per 5 gallons of nutrient. It is an all around good product and compatible with your 3-part. I use it in combination with the next product I recomend.......

Hygrozyme. This product is a good mate with Floralicous Plus because the microbes in Floralicous Plus benefit from the role that Hygrozyme plays. Hygrozyme is a root treatment that aids in the health of your root structure. Your root system dictates the health of your plants, and their yield.