You would need to totally encase them in a none dissolving encasement material so that they have no effect on the water. What kind of fish are you keeping that you need to raise your pH to ocean water levels?
Big help. Learning a lot before I go for a bigger tank. I did have a water check today and it was 7.2 on the ph. Close, I pulled out one shell so far.A lot will depend on your water's chemistry as to which rocks you can safely use.
Quartz, Granite, Slate and Sandstone are an all around list however you need to be careful with quartz as it can have other metals within it. Same with Jasper. River rock, pea rock, Dragon stone and manten stones are other safe ones. Lava rock is also a good choice but there are different types of lava rock so you want to be sure that the one you pick is not high in phosphates if you don't have a planted tank. I used a lot of lava rock, that people complained causes high phosphate levels, in my non planed tanks without issue but I adhere to a very strict water changing schedule so if you don't, be careful of which lava rock you choose.
Hope this helps.
It's not so much the number of shells as it is the amount of calcium carbonate in the shell that will alter a water's chemistry. Obviously, an adult conch shell is going to have more calcium in it than say, a cowry snail shell so the use of shells for water chemistry is a pretty broad statement. Add to that the fact that removing one shell is not going to half the amount of change or calcium being dissolved into the water. It will just make the other shell dissolve faster. This is why people use crushed coral in a filter to keep the water chemistry more stable. As soon as the nitrates cause the pH to drop, the coral dissolves some to raise the pH again but then it's fighting against the acidic nitrates so until the nitrates are reduced, the coral will be dissolving. Once the pH become alkaline again, the coral will stop dissolving. So this becomes a chemistry problem more than a math problem.
Hello. Rocks are generally fine. You can use the vinegar test on the rock. If when you pour a little vinegar on the rock, if there's a reaction of any sort, then don't use it. Old pieces of driftwood that have been exposed to the elements for a long time are fine. You'll need rocks to secure the wood to the bottom. I've found Mopani wood to be especially nice in a tank. It's available online and if you're a good shopper, you can find it at a very reasonable price. It just needs to be soaked in a large bucket of water until it releases the brown, tannic acid color.
