add water to batteries?

Water level in the batteries should be checked on a regular basis, period.

Be careful to not overfill.

Part of my routine maintenance is to check the batteries on the first of the month.

Don't fill the cells all the way up. Cover the plates, add 1/4" more and call-it-a-day. This gives the electrolyte plenty of room to burp without forcing it out of the cap vent. USE WRAP-AROUND GOGGLES! A set of goggles wrapped in a rag can survive for 10-years. Nitrile mechanic's gloves allow feeling what you're working on. Mark the finished level on the water jug with a Marks-A-Lot along with the date.

Your converter should float around 13.4 volts. At 88F this should not cause a lot of water loss.

You don't ever leave the caps off a battery, (if that is what you were suggesting) no matter what the temps are. That is a myth started many moons ago, for who knows what reason. The vents in the caps are much more than adequate to handle any amount of amps the batts will ever receive.

And IMO,.....and many years experience, if you need to add water more than every 6 months, you need a new 3-4 stage converter charger, or a new solar controller.
That's not to dispute the suggestion to check levels every month if it suits you.

For $10 you can buy a dedicated battery filler. Easy to use and no overfilling.

yes

Fill to 1/4" to 1/8" below the split ring that extends down into the cell. Just touching is absolute max. Wear eye protection. Check levels every 1 to 4 months. If water use seems excessive, your float voltage could be too high or your batteries might be getting near end of life.

thanks all