Low KH/pH

Question
Hi!

I have a 27 gallon freshwater tank. It's been set up for about 2 years now. I have 2 gourami's, a tetra, and a betta. I do water/filter changes once a month with a gravel cleaner, have a pet-store rock/pastic plants/airstone as decoration.

My pH/KH has always been kinda low, but I never knew why and the fish always seemed happy. Recently I decided I wanted to add a new fish to the tank. On two different occasions I tried to add a few new tetras and they all died within a day of going into the tank.

I finally bought a good testing kit and tested everything about my water to try to figure out why the fish I had were living, but all the new ones were dying.

Amonia: was very low - almost none.
Nitrites: low
pH: 5 (wow)
GH: 6
KH: 0 (yikes)

So I tested my tap water.  The pH of my tap water is about 7.5, but the KH is 0 right out of the tap.  I'm guessing that is my problem?

I've read a lot of info about using limestone, baking soda, chemicals, etc to raise the KH/pH together. I was thinking of trying baking soda. But I'm not sure how much to add - I read 1 tsp per 50 liters to raise it to 2... but I don't know how much that will raise the pH and don't want to kill my poor fish who are happily living in acid. ;)

In all the things I've read they don't address my exact problem of dealing with with KH of 0 right from the tap. How should I deal with it in the short term (getting the tank up to normal levels) and then, how do I deal with it in the long term (keeping the levels stable while using the tap water for water changes)


Thanks for any help you can provide!!

Steph

Answer
Dear Steph,
Wow zero KH or buffering capacity?!? Unfortunately I am fortunate to have a stable and good water chemistry straight out of my tap so I don't have the experience of adjusting it. But I do read very much on that subject.
No reading of KH is very bizzare, without buffering capacity your Ph will (as you found out)drop and be very low and is subject to extreme swings in the pH level also...Something that is very stressful for all fish.
It sounds like you simply have naturally soft water. The solution to this is you have to add an artificial buffer to keep your pH at a good constant level. Most aquarium dealers can recommend to you products that buffer the water to a specific level. Remember, you'll need to add something that provides buffering capacity not just pH adjusters. Normally I never recommend adding chemicals to your aquarium. But in this case it is vital to avoid dangerous pH drops and swings that are very dangerous to your fish. It is generally easier to raise your pH and buffering capacity then to lower it. Some sources say adding buffered African Cichlid salts when used as directed, will produce water with a stable (buffered) pH of the correct value. And sometimes water hardening substances like crushed coral, dolomite gravel, and limestone rock can help keep your alkalinity and pH at a stable level. This is much less precise, however.

Of course, none of this is all that simple. Because you can't just add some buffering adjents to your water and stop there, you must also remember that new replacement water when making water changes will need to be doctored to accheive the same levels as your aquarium.
I have heard baking soda is good. But sadly I do not have experience using it for any of my aquariums. But I do know that biocarbonate of Soda (baking soda) should both buffer and raise your pH level.

To keep levels stable longterm you'll have to treat all new water and incorporate something like crushed coral or other calcerous medium in your filter or directly in your aquarium. Just remember any change must be very slow to avoid shocking the fish.

This should be easy to do as most aquarists say it is fairly easy to raise your pH and KH than it is to lower it.
Because I honestly don't have that much personal experience with adjusting water chemistry you might be good off by asking other experts on here like Chris Robbins who should be able to help you better than I can.

I will continue to gather information about using baking soda and hopefully get back to you with more info.

I hope this helps a little!
Best wishes,
Karen~