There are several important things to consider for good, healthy hydroponic plant growth:
A balanced, hydroponic
nutrient formulation is the best way to go - especially for beginning through intermediate gardeners.
The TDS level is also extremely important as is maintaining the nutrient solution pH at a level acceptable to the plants grown.
For example: beans and tomatoes require TDS from 500ppm (when seedlings) gradually increasing to around 1500 when
maturing and fruiting heavily. An acceptable pH for these plants is 5.5 to 6.5. If using a liquid formula it should be at least a 2
part formula to contain an adequate amount of sulfur and magnesium - something that single part formulas neglect because of
chemical combination problems.
Aeration of the nutrient solution and plant roots is very important as well. Healthy roots should be white.
Adequate feed frequency is important too. In ebb & Flow systems feed often. This may vary with temperature, size of plants,
etc. but I've found that feeding every couple of hours for a long enough period to fully saturate the roots works very well. If a
growing media with good aeration ability is used it is hard to "over water" because the roots will be properly aerated to provide the very important oxygen they need.