Depends a lot on the size and production of the tree; and also the evapotranspiration rate of your climate (available from your local Agri office at County, or often in local newspapers).

Trial and error... I would opt for a drip system water, for a sizable tree maybe as many as 6-8 emitters per tree. If not that maybe a couple of bubblers under the tree.

Sprinklers would be last choice as citrus trunks don't like being hit by them.

In the end you need to thoroughly wet the soil to the drip line of the tree and to a depth of 18-24 inches once a week.

I had to convert a bunch of my sprays to stream bubblers... and also use the mushroom bubbler you have pictured too. I Have one per tree but the water is coaxed into a well under the dripline. I water every 3 days 10 minutes 2x. If its hitting 95-100+; every 2 days. However, i am on clay soil so its not the same for your sandy soil.
I have found that i have done much more damage under watering in hot weather.
I have another property on sandier soil (Napa). My "temporary" setup has proven superior to the usual system. - - - its just a series of soaker hoses hooked up to a timer. The soakers encircle the tree at the drip line. I run them every 3 days for 50 minutes.

As Johnmerr said - its trial and error -- good luck
George K

It would be imperative, I think, for you to know how much water is actually being applied during each watering cycle. Time is not a good indicator of watering efficiency. Have you measured (collected) the water to determine how much water the tree gets during any given irrigation cycle?

Newbie, you have some special circumstances as you're on very sandy soil, and water will drain very quickly down and away from the root system. I would suggest that you head over to your local feed and orchard supply store, somewhere that supports your local ag industry, and ask them specifically the best way to water citrus in your area. Definitely NOT sprinklers that will broadcast water in typical sprinkler fashion, as John has mentioned, as citrus do not like to be hit by sprinklers or have their trunks constantly wet. And Rhizo is correct in that you'll want to be able to measure volume per watering session, and that will tell you how much you're actually applying per watering session, and see if that measures up to the recommendations from your local orchard supply center. I would follow what your commercial citrus growers are doing out your way, and that should give you the correct amount of water. That, and observing your trees for dryness (leaves folding upward), will give you a clue as to the need to water, or water more. I'm inclined to think in your area that commercial growers are using microsprinklers, probably 4 to a tree set at the trunk and pointing outward to water the feeder roots evenly, as opposed to bubblers set to flood a well, due to your extremely well draining soil. I'd think you'd probably end up with the water just soaking down around the bubbler faster than it could fill up a well, allowing for more even saturation. Betting you'll be told to use micro sprinklers.

Patty S.