increasing water hardness for livebearers

Question
Hello Ms. Fields! Thanks in advance to you and the allexperts website for your invaluable help and advice.

I currently have a 25 gallon freshwater tank with 8 zebra danios, 2 albino corys, and 1 bronze cory (all
pretty young.) The tank is well established with a good cycle, has a sand upper substrate and a aquatic
garden soil lower substrate. There's also has a small piece of wood with a lonesome anubia dwelling on it.

What I would like to do is to gradually convert this aquarium into a heavily planted habitat for
livebearers (guppies, mollies, platies, and swordtails living together, all males.)

What do I need to do to make this transition happen? My biggest concern is water: I've read that
livebearers prefer slightly harder water, and the water currently in my tank is rather soft (and pH
neutral). I've heard of adding baking soda, lime, epsom salts, etc. In your opinion, which and how much of
each substance is best for bringing the water hardness to a level good enough for livebearers? I must admit
right now that I do not own a water hardness text kit but have relied on weekly tests from the local pet
store.

My second concern is whether my existing fish will tolerate the raising water hardness until I replace them
with livebearers, or should i find them new homes before altering the water? Keep in mind that corys are
extremely sensitive to salt (which might be used in some water hardening methods?)

Thanks again for reading my question, I appreciate your help :)

Answer
Hi Roger,
What is your current pH level -- 7.0? Livebearers actually aren't that picky when it comes to pH level and they will thrive at anything from 6.8 to 8.0

I think I wouldn't bother if your pH falls within this range. Its much more important for livebearers (like many fish) to have clean stable water then water that is constantly having to be adjusted that can stress both the fish and beneficial bacteria that keep the water safe.

I would just add some rocks that contain limestone to add a little extra hardness leeching out Calcium, Magnesium, and Carbonate to the tank such as 'texas holey rock' or you can add some crushed coral to your filter to add extra hardness to the water.

To test potential rocks to see if they will cause your pH to rise -- put a few drops of white vinegar on the rock. If it fizzes, then it contains minerals that will leech out into the water.

A heavily planted tank is a wonderful idea and livebearers thrive in such setups. Is this going to be a low-light, medium light, or high lighting setup?

Deciding on which lighting level will help you tremendously in picking out the right plants for your setup. An average of about 2 watts per gallon is best for growing most plants but of course some species require much higher!!

I do hope this helps and best of luck!
Karen~