My GH is around 3, KH around 2, Ca 20mg/l (14 - 26) - which I'm guessing is low. My pH varies around 7 - 7.5 and I need it not to go any higher than that to suit my fish. I passively add CO2 for my plants which will obviously drop my pH and KH and that is why I add it passively, not actively. It makes about 0.5 difference to my pH and 1 degree difference to my KH.All life on earth needs calcium to survive. Therefore all foods have calcium.
Gh boosters come in two types those that just affect GH and those that affect GH and KH.. Those that affect KH contain sodium bicarbonant or potassium bicarbonate will affect KH and PH. Products that only affect GH are primarily made from calcium sulfate, magnesium sulfate, or Calcium chloide, magnesium chloride. These don't affect PH.
The big question is what is your GH and PH values. Or do you have your water utility water quality report. it could tell you what your typical calcium and magnesium levels are. depending on the values you may not need a GH supplement. The biggest issue is if your water becomes acidic the shell of the snail will erode and will not heal. Snails cannot repair shell erosion
Also in my experience the biggest problem is keeping you PH stable . If you just check yourPH periodically at about the same time on the same day you might not seee anything. However I have found that ifI use a electric PH pen and monitor myPH for the entire day I can see it change with lights on and lights off. Typically it would drop with lights off but climb with lights on. And the average PH would slowly drop day by day until water change. I solved my issue by reducing my light levels to minimize the daily chang.Ialso added a decorative sea shell to the tank. The decorative shill would counteract any PH drop but will not increase PH above 7.. Overall my ph varies from 6.7 to 7.3. one snail has no erosion while my second which has some old damage doesn't have any new damage.
Sadly the water report only gave Ca levels, not Mg. Shame.The primary purpose of the sea shell is to neutralize any acids before you notice a PH drop. Sea shells and fresh water snail shells as well as coral are all primarily made of calcium carbonate. I don't know of any shells or reasons why some should be avoided. Yes they will add calcium to the water which the snail can use. but most importantly it neutralizes acids.
In my experience the only thing you have to worry about for snails is PH. You don't want acid etching the shell. The shell is a lot like hair. it is not alive. and the snail cannot repair any damage to it. The snail can add new shell material near the opening. but that is about it. Your GH and KH should be fine for snails.
Where did the 20mg/l come from a water report? If so did it mention what your magnesium levels are?
Ooh, I don't know. I've noted it under the hardness section in my journal, but it was all data from the water quality report, so I'm not sure if it was just Ca or not.Where did you find the calcium level, in the water quality report or under hardness? If it was in the water quality report, that is the actual amount of calcium; if it was listed in the hardness section, it is not a measurement of calcium.
My younger son used to work for a water testing company and he explained that 'hardness' is a measure if the divalent metal ions in water. In practice, this means mainly calcium and magnesium with trace amounts of other metals. But they can't list hardness as "x mg/l calcium and y mg/l magnesium and z mg/l this and a mg/l that and b mg/l the other". So they treat it as though it was all calcium, or all calcium carbonate, or all calcium oxide.
So when a water company gives hardness as x mg/l calcium, that calcium includes all the other divalent metals as well. When they give it as mg/l calcium carbonate, that also includes all the other metals.
But if it was in the water quality report, that is the actual level of calcium. My water quality report does not include calcium, which is why I asked.