The short answer is no. If you are:
Doing frequent and large enough water changes with clean water
Your water chemistry (GH/KH) is where it needs to be
... then cuttlebone isn't needed at all. But let's dive into the science a little more. If you have no idea what we are talking about when we say water chemistry or GH/KH, check this video out. It will help explain some things to help you understand this article a little better. But let's move on to...
What is cuttlebone made of?
Cuttlebone, also known as aragonite, is made up of calcium carbonate. Do you know what else is made of calcium carbonate?... Your snail's shell. Crazy, huh?! Egg shells are made of calcium carbonate.
What does cuttlebone do in our aquarium?
When calcium carbonate is put into an aquarium with water that has a PH lower than 7.8, it will start to dissolve. When it dissolves, it breaks down into:
Calcium - Raising your GH
Carbonate - Raising your carbonate hardness, or KH, which also has a large impact on your PH.
The lower your PH, the faster the cuttlebone will dissolve. As it gets closer to 7.8, the rate at which it dissolves will slow, and the cuttlebone will stop dissolving after the tank's water arrives at 7.8. A great example of this is coral in a reef. Coral is made of calcium carbonate and does not dissolve in the ocean because ocean water's PH is around 8.0-8.3. This is why ocean acidification is a problem. If our ocean's water gets too acidic, it will start to dissolve our world's reefs.
So why add cuttlebone to your aquarium?
Cuttlebone or calcium carbonate, is not bad to put in your aquarium, it just has a specific use case. It is a cheap and natural way to increase soft water's hardness (GH/KH/PH) back up, leaving the water's PH around 7.8.
What do people think cuttlebone is doing in an aquarium?
Most people adding cuttlebone ignorantly think it's going to provide a slow-release calcium supplement for their snails. The truth is that it won't do anything if the tank's PH is already above 7.8. And if the PH is lower than 7.8, it will only dissolve enough to raise the PH back up to 7.8, and no further.
Why do we not like using cuttlebone?
Cuttlebone is a natural process, and a natural process can not be controlled. In an aquarium, the more we can control, the more successful we will be! As talked about in our Water Chemistry video, we have total control over our GH and KH using remineralizes, and (bi)carbonates. We know that if we put 10 grams of baking soda (sodium bicarbonates) into 20 gallons of water, it will raise our KH up 4.25 degrees. ASG thinks it's better to rely on things we can control so that we are not just tossing a compound into our aquarium and hoping for the best. ALSO, what if you want to push your PH beyond 7.8, then cuttlebone won't work. You'll need to rely on baking soda (sodium bicarbonate) or soda ash (sodium carbonate) to get your KH/PH up beyond what cuttlebone can naturally do. Take control of your water and create an environment in which your snails will thrive!
What should we be doing instead of using cuttlebone?
We should ALWAYS research the specific needs of our livestock, including the water chemistry (GH/KH/PH), before we add it to our tanks. We suggest adjusting our water's chemistry through remineralizers, carbonates supplements, and RODI water if needed, instead of with chemicals (looking at you Seachem) and/or natural processes. GH is the measurement of your water's calcium and magnesium. If your tank's GH is where it needs to be for snails, there will be enough calcium in the water for your snails. And if we are processing large enough water changes frequently as the ASG method teaches, 50% weekly, we'll be replenishing these minerals so the snails will never run out of calcium. It's really that easy.
What water parameters should we keep our nerite snails in?
According to an article written by Modestfish.com, the ideal environment for Nerite snails is:
Temperature: 72°-78°F (22°-26°C)
Ammonia/Nitrite: 0
Nitrate: <30 ppm
pH: 7.0-8.2
GH: 5-8 dGH
KH: 5-15 dKH
We hope this article sheds a little light on what calcium carbonate does, and why it's not a great idea to use it with your snail tank. Watch our video on water chemistry below, get yourself a test kit and some Seachem Equilibrium and baking soda, and take control of your water parameters.
Tap water does have minerals in it. All water does except for distilled water.
You stress that doing large water changes would keep your water parameters in check, but that’s not always the case. If your water doesn’t have many minerals in it, your water changes won’t be replenishing anything. Something worth noting for beginners: test your water before it enters the aquarium so you know what you’re working with