Your link just gets me to a page with various rock, and gravel products. But I think you might be talking about the wonder shells or something similar. I am new to adjusting the GH of my water but here are some of my observations.
I have one tank that I use a very porous limestone rock to try and push the GH up a bit for the snails and guppies. It is not very efficient in driving up the GH but I also do large water changes so the lack of change in GH is expected. Also the longer the limestone sits in the tank the less effective is seems to become. I believe you get a better result if you would use a calcareous substrate but that would also mean bigger shifts in the GH over time if you do large water changes. Mine raises the GH in the tank from 10 to about 30-50 but I also don't do more than 35% water change/week on that tank.
In my new (7 months) shrimp tank I decided to control the GH of the tank and use
https://www.seachem.com/equilibrium.php for that. It seemed the most cost effective compared to other methods and doesn't add NaCl. And with the mixing the water the replacement water should be close to or the same GH as the remaining water in the tank causing fewer issues with the creatures. The side effect of Equilibrium is my pH in my shrimp tank is high 8.2 to 8.3 but the shrimp so far don't seem to mind it. (I made a spreadsheet to calculate the dosage because my city water does vary from time depending on season and treatments for pathogens) In this tank I change 20-25 percent of the water. This is a bit of a process. I use TDS meter to determine the GH using a previously calculated TDS to GH ratio for both my source and tank water. Then for every change I take a tds of the source water, calc the equivalent GH and decide how much adjuster (whatever it might be) to add to the source water before dripping it into the tank.
All that said I have snails in my non-GH adjusted tank which is at 0 -10 ppm of GH (my water has no minerals in it), the snails include bubble snails, nerites, and ramshorn snails. All of them actually seem to be doing well, the nerites are the only ones I bought and they are 1.5 to 2 years old now and their shells seem OK from what I can tell. The ramshorn and bubbles have gone through some generations. Additionally, the substrate is fertilized with the sechem tabs, I suspect they get some of their minerals from either scraping the rocks, they are non-calcareous in this tank, or from the food they eat. This tank has an overly large number of angels in it so I do a 70% change on the water weekly. This is easy because the tap water is the same as the tank water. It also keeps my NO3 in the 5ppm range.
Overall if you need to adjust your water because your GH is quite low but you want creatures that like high GH water, I think it is best to do that where you have full control over the GH (Replenish, Equilibrium etc) as opposed to methods where something slowly disperses through the water (wonder shells, limestone, crushed coral) slowly driving up the GH. But if you only need a little change in GH I think you can get away with using less direct methods of controlling the GH. I don't bother trying to control the pH, I find it a lot more sensitive overall.
Just my opinions.
