Hi Mariano, are you sure you are new to hydroponics?
Your setup and your cultures look great and I think you doing very fine!

As you are doing so well, I wouldn't change much anyway and not consider to much other options or alternatives either. Don't change a winning team as they say!

Although the total EC of 2.5 seems extremely high (especially for the smaller plants and herbs), it perhaps keeps your PH that constant and the results speak their own language. But yes, different plants and plant sizes need different EC. The reservoir doesn't seem too big to me from a purely optical point of view. Perhaps you are waisting some nutrients with that setup, but if you change it in order to make sufficient economies, you may screw it all up in no time! You can always fill up your reservoir with a little- to distinctively less nutrient solution - and constantly monitor PH and conditions of your plants. If something seems not right, add more again.

I lost all of my rosemary (from growing tip clones) in my setup with much lower nutrient concentration even after they took root pretty well. They had the same symptoms as yours. I was wondering about the reason but have no answer yet. The only clue I have is that they do not like excessive watering and humidity and ask for different conditions than ordinary.

In your case I would rather suggest to isolate or take out the rosemary. Transplant to garden for example, if this is an option for you. If only the rosemary doesn't fit into your setup, you anyway shouldn't change your concept - but rather take out what doesn't fit in. Oppression or disrespect of minorities doesn't actually apply with hydroponics ;-)

PS: If someone has a hint or clue about how to grow rosemary appropriately with hydroponics, I would be glad to know about it.

I can't speak to hydroponics, but I have some rosemary growing in a pot on the back deck. I know it is a drought tolerant plant, so I would suspect too much water is what is causing the problems with them.
As for aeration, I've read the same thing. Though most hear swear by an air pump, I believe a waterfall effect is supposed to provide better aeration to the water. Since you're using Enf though, aeration is not too much of a concern. the plants get their air when the nutrient drains away from the medium and draws in fresh air.
As for your nutrient levels and EC; spend some time figuring out how to calculate concentration from the concentrates you have. then you can build your reservoir to the desired concentration. next measure the EC of the fresh batch and try to maintain that EC levels for two weeks or so until you switch out your nutrients.
I water my peppers about 2 minutes every hour during the daytime. every 45 minutes during peak heat of the day. so your watering may be a touch too little, but I don't think its anything to worry about. you appear to be using 3" netpots, so you have more medium to retain moisture than my plants do.
Nice looking setup BTW. do you have any issues with algae?

I'm new to hydroponics as well, and I am also using pure blend pro nutrients. I used the amount that was on the label and my ec was around 2.8 (which I was told is way too high for peppers). I was seeing the root tips brown as soon as they hit the water. My pepper plants are about 16 inches tall with five to seven peppers on each one. I lowered my EC to around 1.0 about 10 days ago and still see the same growth rate, but my roots appear to not be browning at the tips anymore. Also, I am saving money buy using a lot less nutes.
As for the rosemary, I agree with grizzman. I have some in soil, and always let the dirt get pretty dry before watering. It seems to like the dry side of things.

Thanks for all the replies. I am learning something new every day. For example, the day I wrote this, I changed the nutrients to EC 2.5 and all of the roots today are completely brown. What you see hanging from the basket up in the picture are completely gone.

So here is what I gather from all of you. I'll lower the EC, probably start at 1.8 going down. From what I read and my recent experience, I'll try to figure out a way to start easy on the nutrients, e.g. when I flush a tank I can go half strength or less and keep going day by day until I reach my setpoint. Hopefully that won't stress the roots.

Regarding aereation, I'll leave it as it is. I also thought that an ebb and flow gets air when drained. I just need to watch the temp of the reservoir. Not much I can do on this one, but might explain nutrient deficiencies if I ever get one.

Rosemary going to the ground. I might create another setup running on a separate pump and run it a bit dry. In the meantime, I'll get this little guy to the soil. It'll do better.

Regarding the algae question, I don't know as they don't have time to grow. The reservoir gets cleaned every two weeks, sprayed with bleach and flushed. The containers (clear Sterilite type) are painted black and also bleached once a month.

After some experimentation, I found this to be the best setup I could come up with. All the hoses allow me a quick disconnect and a partial shutdown for cleaning and sterilizing. I can grow by adding more containers and pumps easily.

The only thing I am working right now is a controller for the setup. I currently have a programmable timer, but trying to build a smart controller that will have a light sensor, a temperature sensor and, maybe, a humidity sensor. This way I can adjust the watering for different containers using the same reservoir.

Thanks all for the feedback! I'll post some pictures of the progress in a few weeks... when I get the germination process right (this is even worse for me).

Thanks,
Mariano