How do you raise KH without raising pH?

[yhbae]

My tap water is soft (probably too soft for general use, at 2dH for KH reading). pH is 7.2. Understandably, pH can swing easily. Great water for breeding tetras but not great for low maintenance community tank... (I am almost done with cycling - I will probably be ready to add the next pair of fish within a week).

I've been adding baking soda (very small amount) to raise KH to around 4 and pH to 7.8 (which I don't like). So, if I add a drift wood (or add small amount of peat), will this lower pH without lowing KH? (My understanding is that it does lower KH, which means baking soda and peat cancels each other out! ).

I don't want to start adding those chemicals that messes with water chemistry.

Any sensible options besides "giving up" fishes that like low pH?

 

[ChilDawg]

Um, it seems as though fishes that like low pH would be fine in your water because of the inability to buffer it...just a little peat moss will help lower the pH. You'd be more SOL if you tried to keep fish that love high pHs without adding buffers like crazy.

 

[carpguy]

pH and KH go hand in hand. Raising KH will raise pH, all other things being equal.

You could use CO2 to drive down pH for the higher KH. This would be ideal if you were planning a planted tank.

You could live with 2dKH. Its low, but if you keep an eye on things its not necessarily too low.

And fish are adaptable. 7.2 should be fine for a community tank.

 

[wetmanNY]

With alkalinity reading 2 degrees of hardness, your pH of 7.2 sounds a little elevated. Perhaps you've been "adjusting" the water too much.

Do a good water change, and provide a little stabilizing buffer simply by adding a couple of tablespoonsful of crushed coral (aragonite) to your filter.

You don't need any more KH than what will stabilize the pH in your particular system.

Plants and softwater fishes will thrive in such water, I can tell you from personal experience.

As long as you have a thriving community of plants, ammonia will be taken up, even if your pH drops into the lower 6s and nitrification is slowed. No ammonia will accumulate (it would be ionized to nontoxic ammonium anyway), and with slowed bacterial nitrification, nitrates won't even build up much.

You should be able to run such a system with nitrates ~10ppm or less.

 

[ChilDawg]

Is that pH straight from the tap or after letting the water sit for a bit?

 

[yhbae]

This is the water 24 hours after from the tap. I understand that pH of 7.2 is probably good for 99% of all the fishes out there. The only concern I have is the pH swing - from what I have learned so far from here, wrong pH is better than changing pH. With KH sitting at 2 (or less), wouldn't pH swing easily?

Just to confirm, my tap water, after 24 hours, reads pH 7.2 and KH 2, GH 4. This is with zero additives.

 

[ChilDawg]

pH is less likely to swing if you keep up the tank maintenance...it usually crashes when you let the tank go without being cleaned for a while.

 

[yhbae]

I will be doing 20% water change (including gravel vac each time) weekly at least, and the tank is well stocked with Java moss and ferns. Hopefully, this will be enough to maintain the tank.

I still prefer if I can somehow achieve close to pH 7 and magically raise KH to around 4 or so and not worry about sudden drop in pH...

 

[ChilDawg]

I wounderstand that you'd want to do that...and it sounds like a good idea. Perhaps a small bit of coral gravel mixed in with your regular gravel would help things...maybe someone else can chime in on that!

 

[yhbae]

Originally posted by wetmanNY
With alkalinity reading 2 degrees of hardness, your pH of 7.2 sounds a little elevated. Perhaps you've been "adjusting" the water too much.

Do a good water change, and provide a little stabilizing buffer simply by adding a couple of tablespoonsful of crushed coral (aragonite) to your filter.

You don't need any more KH than what will stabilize the pH in your particular system.

Plants and softwater fishes will thrive in such water, I can tell you from personal experience.

As long as you have a thriving community of plants, ammonia will be taken up, even if your pH drops into the lower 6s and nitrification is slowed. No ammonia will accumulate (it would be ionized to nontoxic ammonium anyway), and with slowed bacterial nitrification, nitrates won't even build up much.

You should be able to run such a system with nitrates ~10ppm or less.

Now this sounds alot better... I always wondered how people manage to keep community tank with sub-pH7 water since KH and pH are supposed to go hand in hand.

So can I add driftwood/peat and try to settle my pH around 6.7 or so, and ignore my KH level? Other than Platy (which my 5 year old picked), all other ones should handle this level of pH easily (Gourami, Cardinal Tetra, Cory, Otto). Heck, Platies are supposed to be hardy (hence I am using it to cycle), so it will probably adopt easily...

As I mentioned above, I already have decent amount of Java moss and ferns. I can see that even though my first cycling is not complete, they (plants) seem to thrive and multiply!