yes you should slowly replace the lost water. Check for Ice dams diverting the water outside the liner and think about pulling the pump so the pond does not run dry.

Excess dropping of old leaves is in fact often caused by watering problems. However, nutrient deficiencies can also produce this condition. Summer is a common time for broad-leaved evergreens to drop spent leaves, sometimes this occurs much of the summer. If you are being left with a full dense covering of large healthy leaves maybe there is not a problem. If the plants are becoming gaunt- or tufted-looking then they are declining and you need to discover what the specific issue is, rectify it. Common causes of such difficulties with new plantings are drying out of intact, undisturbed rootballs and amending of planting hole backfill. Sun beating on unmulched root zones, particularly in hot locations can also be a source of distress for new shrubs. What you want is a uniform soil texture throughout the entire rooting area, protected from the sun (and later, the cold) by a coarse mulch. Intact potting or field soil rootballs are liable to shed water to finer-textured native soil around them. The same thing results from liberal amending of planting hole backfill, where this results in a different soil texture within the planting hole than without.

Below is a link to salt test strips. You can probably find them locally as well. Quote: "Free chlorine = total chlorine" Are you saying your testing is showing no combined chloramines? Because FC does not equal TC, TC equals FC plus CC. If your CC is zero, then yes, TC does equal FC. But the point is your pool uses more FC in the summer due to the heat and bather load, you don't necessarily see that reflected as CC in testing though. Also direct sunlight burns off FC. Since the sun is higher in the sky in the summer and out for a longer period of time you lose a lot more FC. The lower your CYA the more FC will be burned off by sunlight. This also will not show up as CC. Here is a link that might be useful: http://www.tftestkits.com/index.php?act=viewProd&productId=5

In a water test there should be zero drop in pressure. In an air test there is a few minutes where the needle bounces since air compresses that way. Water does not. When I bleed the brakes on my car there is zero drop in pressure as soon as I close the bleeder valve. Same thing here. I have no confidence in your current technician if he does not understand the basics of pressure testing. At least he is testing to a reasonably high psi, but the test clearly indicates a leak somewhere in the system. Did he spray his tester with soapy water to make sure it is not the reason for the loss? Also, 40 psi is dangerous, he should be tying off his tester and you should be careful if you are around it / anything that is under 40 lbs of pressure.