Forgot to mention,
ended up using a Raspberry Pi to monitor the Temperature of the aquarium.
using ds18b20 temperature sensors.(plastic cap version, so that it does not rust )
https://www.sparkfun.com/products/11050based on HydroPi that i modified a bit to make it do what i want.
https://myhydropi.com/raspberry-pi-pool ... ython-codehttps://myhydropi.com/raspberry-pi-pool-monitor-websitethere is also the ability to add PH, ORP, Dissolved Oxygen, Conductivity etc using Atlas Scientific sensors later on.
https://www.atlas-scientific.com/kits.htmlIntegrated my Solar inverter's info into the status page. using the Fronius Primo API.
all logged every minute, and stored into MySql database. data can then be graphed.
data also made available via SNMP, so i am also using my PRTG server to log and graph the data.
no relay connected. have not played with the alerts yet. (i can either do it straight from the pi or via PRTG)
pi with all the temp sensors connected

main status page ( the State will change to RED if it is too high, or BLUE if it is too low) [no https configured yet]

graph for last 24 hours

graph for last 7 days

pretty cool that you can actually see when the heater turn on, what temp they turn on, what temp they turn off.
p.s sump is for my fresh water aquarium..... not for the marine aquarium, hence why the temperature are different.
Still a work in progress.......