Proper alkalinity for Mollies?

[TatteredOcean]

Hello,

I've been keeping fish for roughly six months(not counting when I was a child and had bettas & goldfish in fish bowls). I've had Mollies and once a male Betta + six ghost shrimp in a ten gallon, but I've never EVER heard of alkalinity before until yesterday when I brought some tank water from my 20 gallon Molly tank to petco to get tested(My test kit still has yet to arrive) and the person working at the aquariums(who actually knew a lot about fish) said my ammonia, nitrites, and nitrates were perfect(I don't remember the actual numbers) but the Ph and Alkalinity was too high, at 7.5/8.0 Ph and like 350 for alkalinity(my memory is pretty fuzzy right now) I've never heard of alkalinity and was too shy to ask(I'm honestly surprised I managed to ask them to test the water). She told me that I should get some drift wood to help lower it and I probably shouldn't add any fish as it'll probably stress them out(which is why i didn't get the balloon Molly that was being pestered by the males :/). I've searched a lot about alkalinity but haven't come across what the proper alkalinity for Mollies would be, could anyone tell me?

(My fish and Ghost shrimp are doing perfectly well despite the high alkalinity)

 

[OrionGirl]

High alkalinity really is not the problem. In the wild, mollies are found in waters much more alkaline (and more base, as well) than your tank. Low alkalinity can cause issues with pH being unstable, but high shouldn't cause too many issues.

First, though, you will need to know why your water chemistry is this way--is your tapwater high alk/pH? If so, changing it for your tank is not going to be an easy process, and unless you want to keep wild caught species from soft waters, or want to breed them, likely not worth the effort and stress. Adding things like driftwood, or other sources of tannins, will reduce the alk and lower the pH, but not in a controlled manner, and fish will benefit from stability far more than from a specific number (they can't test alkalinity, really). Adding tannins will increase TDS, which in the long run is less beneficial.

If your tank pH/alk are high and your tapwater levels are low, you will want to determine why. Perhaps there is a decoration or substrate that is calcium based, and causing it to go up.

If your water is vastly different from the water where you buy your fish, you might want to consider drip acclimation to gradually introduce the fish to your water from the water at the fish store.