There are currently 5 versions of the Apex you can buy new.
- 2016 Apex
- this is the recently replaced flagship model. It is almost the same as the new A3 except this one has salinity monitoring and the A3 Apex Pro does not but has a fluid monitoring module instead.
- Apex EL
- This is the old mid range module. It lacks the salinity monitoring of the 2016 Apex as well as the 0-10v ports and ORP probe but is otherwise the same.
- A3 Apex
- This is the new base model The same as the flagship minus the 0-10v ports ORP probe, and extra FMM ports
- A3 Apex Pro
- This is the new flagship model no slainity monitoring but an advanced level sensor, leak sensor, and ORP probe.
- A3 Apex Jr.
- This is the cheapest option and it is the only unit that does not include a power strip or ethernet port. It has temperature, pH ,leak, and level sensors but no ability to turn equipment on or off.
Currently, there is no way to monitor Phosphate with the APEX. None of the base units can measure calcium alkalinity or magnesium on their own but all of them can when you add a trident which is an additional add on you will need to purchase if this is important to you.
Based on what you have said you are looking for the cheapest way to get the functionality would be to get an A3 Apex Jr plus a trident.
I would strongly recommend you step up to either the Apex EL or A3 Apex as these will give you a power strip so you can turn things on and off like malfunctioning heaters, faulty dosing pumps, or pumps that are running dry. This is the most important part of a controller IMO.
