I agree with the OP - you need a way to manage your nutrient solution temperatures. I would recommend 66 to 69 degrees F (18.9 to 20.5 degrees Celsius)
And yes 5.7 to 5.9 pH is ideal for Hydroponics but you do have some wiggle room.
Chillers can be expensive, until you are able to acquire one, You can utilize products like "UC ROOTS" or "Watermax" or other products that contain Hypochlorous Acid which increases the ORP value of your Nutrient solution and makes it more Bacterial Static.
Your air pump is a good size at 16 liters per minute for your approximate recirculating volume of about 20 gallons.
You may need to consider adding more Opacity to your grow modules to seal out light infiltration within your root zone, otherwise it looks like you are ahead of the game for a first time Hydroponic grow.
likes 2