What components do I need to purchase for the project?

Question

Arduino

The crux of the matter is that there are three lizards (eublefar, banana-eater and bearded agama), for all this brethren a large rack with three terrariums is being built, certain comfort conditions are necessary for each lizard, but since we are stoned people, I decided to occupy myself with automating the maintenance of these very conditions.
Well, in case of departure, so that the pets do not throw back their paws.
As I see it:
- There are settings for each of the terrariums (light (day \ night) and its intensity, UV, heating and humidification)
- There are sensors for humidity and temperature so far (we take readings from them and if something is out of the norm we twist it up to necessary)
- Sensors for failure if something burns out and breaks
- The server on it stores the changeable system settings, we receive alerts in case of failure of any block and we also receive statistics from the sensors in the database, so that we can later pack it into a web interface / apache
- A tablet with a browser / application to display the necessary information for each terrarium directly on the rack, Schaub was pretty.
By temperature: ideally, several sensors to measure the temperature gradient. The terrarium has a warm and a cold zone.
By humidity: there are two sensors in the humid chamber and a common one for the terrarium.
Well, against the background of all this, the question arose of how much and what to buy (at least approximately), one arduino per terrarium or from all for one board, or even several boards. Well, for consumables, sensors, adapters and ethernet outputs.
Because if it’s not a problem to assemble the software part, then I didn’t work with pieces of iron and there may be plugs so that they don’t kill anyone later because of my little hands.
Thanks in advance for your replies!
UPD I will add info to make it more constructive. From what I googled (based on 1 terrarium, approximately):
1. The Arduino board itself
2. 3 waterproof temperature sensors (warm / cold zone, common)
3. 2 humidity sensors, (general and in the humid chamber)
4. Ethernet module to merge
the information 5. Time relays for light and heating
6. Cooler for forced ventilation
7. Windshield washer pump + tubes and a nozzle for spraying water.
8. Development board In
general:
1. hub
2. common water tank + level sensor
3. some box where to stuff it all
4. solve the problem with powering all this
5. uninterruptible power supply
By spraying water, I think so for a couple of cycles (conditionally spray water several times: D):
- Turn on by the timer
- We turn on if the humidity has fallen below the lower
threshold trace otherwise).

Answer 1

Even if some kind of self-made "smart house" "revolts", its smarter owner should theoretically have time to run to the switch. You are talking about the safety of dumb living creatures.
In your question, I, as a certified design engineer, see many hours of design, various calculations, incl. and system resiliency. Then field tests, MTBF, failure tests of various sensors. In general, a year and a half of work will run up, and then this will not give a 100% guarantee of the safety of your little animals. In short, only one project is a question for more than one thousand dollars, I googled, your animals don’t cost that much, it’s more like a topic for a small startup. In your case, ask the neighbor woman Masha to look after the living creatures and all the automation.
PS

8. Breadboard

He smiled frankly. Although in other matters, your entire list indicates your flayer inclinations

Answer 2

On the one hand, one Arduina mega should be enough for the eyes (look at its characteristics: fifteen years ago phones did not have such performance), on the other hand, connecting a dozen sensors to one arduino is not a very rewarding task. But to synchronize communication with a bunch of independent devices, as for me, is still hemorrhoids. So look here: if you want to dig into the pieces of iron, take one arduino, and if you want to play hardcore, take several.
It is certainly possible to connect several controllers to one ethernet, but personally I would not undertake it, it is clearly pointless to make several ethernets per controller, so my advice about the number of ethernets is exactly as much as arduin. You just need to keep in mind that all these ethernets must go somewhere, and if the "server" you planned is actually some old laptop, then, if there are a lot of arduins, you need to take care of buying a hub.
As for the sensors, you yourself clearly described everything, except that your zeal for fault tolerance, although it does you credit, is most likely somewhat redundant: a sensor failure is still nonsense, and it is unlikely that you really need it. But really, it's up to you.
As for consumables, I note that at the time when I was doing a similar project, I really lacked a variety of wires (both in color and in length), but maybe this is just my problem.

Answer 3

The presence of an arduino increases the likelihood of death.
I would put dedicated specialized devices on the main things, separate controllers for temperature, humidity and lighting.
As a last resort, divide into 3 separate controllers, each for its own terrarium, in order to avoid genocide.