It is always a good idea to check with your battery manufacturer and obtain the recommended ABSORPTION, FLOAT and EQUALIZATION voltages. You will then program your charger to your batteries using the preset charge algorithms. Some chargers offer very little in the way of "smart" charge programs, sometimes four or less, and others, like this Sterling, offer plenty of options. As mentioned the Sterling PCU chargers also offer a user defined program that you can self program. Very cool for those applications that need it.
You can always choose to use GEL or AGM settings on wet cell batteries but a good quality charger will not go into equalization mode, and should not, while in AGM or GEL mode. If charging WET batteries with a GEL or AGM program you'd need to switch back to a WET program to equalize your batteries. In contrast you should NOT use AGM or WET settings on GEL batteries.
Just a note on equalization. Sulfation is like cancer of the battery, once it has set in it is only a matter if time before the battery passes on to battery heaven. Equalization is like Chemotherapy. It helps prolong the life but only prolongs the inevitable for some time. DO NOT over equalize your batteries as it can cause plate decay and lead to shorter life if over done. The best thing you can do for your batteries is keep them at or near 100% state of charge as often as possible. If on a mooring this will require wind or solar as an alternator simply won't do this and the batteries will sulfate prematurely.
I much prefer to equalize batteries ONE AT A TIME and monitor the progress with a hydrometer or, what I use, a sight refractometer. A good charger with temp sensor should monitor the temp but it never hurts to have a digital infrared thermometer on hand while equalizing. Please DO NOT equalize batteries unattended! It is very wise to be there during equalization. If you are unfamiliar with equalization PLEASE research this before hitting the button. To equalize one at a time simply disconnect the batteries not being equalized.
Thoroughly test your charger before leaving it to do it's thing. I personally don't like "unattended" charging even with the best built chargers in the world. This is just MY personal preference, so consider it, but don't take it as gospel. For unattended charging I use solar. It works for us, but may not for you.
Unfortunately for many boaters in warmer climates, with WET cell batteries, the ambient temps require that chargers be left on and most often "unattended". This is due to the exacerbation of battery self discharge in warmer temperatures. Heat kills batteries, cold helps prolong life.
Sulfation and self discharge greatly accelerate the warmer battery temps are, so do keep your batteries topped up as often as you can. In a perfect world all chargers would perform flawlessly for 20+ years. Sadly for the boating public we don't live in a perfect world and many a charger has taken out a perfectly good bank when it decided to pack it in, I see it OFTEN. When owners leave a charger on constantly when the charger fails it often takes the batteries out with it. This simple charger failure now becomes an entire new bank and a new charger as opposed to just a charger. If you don't need your charger on constantly consider NOT leaving it on and unattended, if you don't absolutely need to. Balancing unattended charging & its potentials for failure modes, versus the potential for self discharge and the resulting sulfation is one you'll have to tackle on your own.
Good luck with your installation!!