Hello Reddace,
I don't know what advice your looking for, but for me personally I don't like to use water culture systems for long term plants (plants that will be in the system longer than about 2 months). In those cases I like having the reservoir separate from the root zone. Mainly because long term plants aren't really that small, and having the reservoir separate from the root zone makes maintenance easier, while still being able to easily accommodate the root size/mass when the plants reach full size. But I guess my advice for long term plants in a water culture system is:
1. Make sure you design it to be able to support the plants when they reach full size. Both in top support so the plants don't tip over, and water volume (
What size reservoir do I need). Most of the time people will build their hydroponic systems without thinking about how big they will actually get, and the plants outgrow the system before they get a chance to harvest anything from them.
2. Make sure you design it so that doing maintenance (checking and adjusting pH,
nutrient changes, replacing the water the plants drink) will be easy and withough't harming the plants. If doing the regular maintenance becomes a chore, you will neglect doing it, then your plants will suffer because of it.