The pH color scales are hard to read. I like the digital pH pens, https://amazon.com/s/ref=nb_sb_noss?...+pH+test+meter, which are not that expensive, and easily read. Whichever one you pick, be sure to get some of the calibration solution or powder to check calibration periodically, as they do drift some, but even drifted they are closer than the eyeball on the color chart. As was mentioned, you also need to get the KH test kit, as it is more important than the pH test in my mind. Depending on the well, the water may be near devoid of any buffer(usually very soft water), allowing the pH to drift all over the scale, or it can be high hard water with a high carbonate, which will be well buffered with a good KH. If the KH is lower than about 100ppm, then the addition of baking soda will be the cheapest and easiest way to get the pH buffering. The use of baking soda will peg the pH at about 8.3 or 8.4 but that is not a problem, rapidly changing pH is a problem. Hard water typically comes from sources of limestone type deposits and to dissolve the limestone, the water has to become acid, and oxygen depleted, so the information given above is absolutely necessary about spraying the water in. The acid is carbon dioxide dissolved in the water from the carbonate rock dissolving, and it is vented out quickly by the spray. Some wells have dissolved hydrogen sulfide, making the water smell of rotten eggs, and that gas is highly toxic to the fish, but if this is your drinking water, I would not anticipate that being in the water.
All surfaces are places for the good bio bacteria to populate, given good oxygen and food source, which requires flow, so some of the rock is acting as part of your filtration. You need to look into some form of filter that is outside the pond, to take the bio load. The sand gravel filter of birdman, is a good cheap filter that should take care of most of your bio load, but filtration provided by most of those garden pond installers is usually pretty minimal.
As for pulling the foam off, I don't think you can pull a tear in the liner. That stuff is tough. Temporary quarters for the fish when you take them is easily provided using the https://www.walmart.com/ip/Intex-10-...-Pool/40720864.
Zone 7 A/B
Keep your words sweet. You never know when you may have to eat them.
Richard