KH is carbonates.
Adding any product that contains carbonates (including tap water if it has carbonates) will add carbonates to the tank water.
Carbonates are a buffer that can affect the pH.
pH is not that critical to many fish, it is the mineral level (GH, KH and TDS) that is more important.
Some of the things going on in the tank can lower the carbonates. If there have not been regular water changes then the reduction in carbonates can continue until the test reads 0 degrees KH.
If you do regular water changes with water that has carbonates (almost all tap water has carbonates) then the tank water will show carbonates that stay pretty stable, and similar to the tap water. Longer time between water changes and the KH can cycle between high (tap water) and reducing levels as the various processes use up the KH.
The pH will usually follow the KH variations. When the KH is high the pH tends to be high. As the KH drops the pH is more free to do something else, dictated by something else in the tank. Often this is organic acids, so the pH usually drops when the KH drops. Not always, though.
Sudden changes in mineral levels are not good for fish or other aquatic organisms.
If your tank is showing a slow drop in GH, KH or TDS then you can supplement in any of several ways.
1) If your tap water has the right levels, then do larger, more frequent water changes so that the levels stay closer to where you want them.
2) Add a natural source that dissolves slowly in the water. Coral sand, oyster shell grit (sold for caged birds), limestone sand or gravel and similar materials will dissolve more in acidic/low mineral water and less when the pH, GH, KH and TDS is higher. This is a naturally regulating source of the minerals that the tank may need. You cannot rely on them to dissolve immediately when you do a water change, though. When I use these materials I make up the new water to match what I want the tank to be and rely on these materials to keep the tank stable through the week. For hard water tanks (live bearers, Rift Lake fish) I keep some of these materials in a nylon stocking in the filter.
3) Use faster acting materials, at smaller doses to gradually change the mineral levels in the water. Do not use so much that the mineral levels take a sudden jump.
I use baking soda (sodium bicarbonate) for KH, Seachem Equilibrium for GH. I prepare new water in a garbage can, and use a fountain pump to circulate and dissolve these materials. I make sure the net result of the water change will make the tank water not more than 15% harder or 10% softer than what the fish were used to. This takes a bit of math to work out, but is actually pretty easy.
I have also added these materials directly to the tank, dissolving them in a small amount of water, then pouring them in directly in front of the filter outlet or power head. Make sure the dose is right so the change in mineral level is not too great at any one time. It takes a while for fish to adapt, but a change of 15% higher at any one time can be repeated about twice a week.
My info is based on keeping many types of fish, including some that were quite delicate and could not tolerate swings in water mineral levels.
I am not sure about Bamboo Shrimp. Are they sensitive to some of the ingredients available on the shelf? I do not know.
How much of a change in mineral levels can they tolerate? I do not know.
Is pH more important to them than it is to fish? I do not know.