KH/Ph/Acid Buffer. Confused.

[Wulfy]

Ok, I have been running my new Aquarium for a few months now. I used to keep Goldfish and some platties and Bettas before. Nothing sophisticated, feed, water change, remove dead fish.

I want to do things right now because I want to keep
discus and I know how picky they are about H2O quality.

The tank has cycled but I am puzzled about the Ph/KH/Acid buffer relationship.

My Ph is around 6.4-6.6, my CO2 seems to be stablizing
it finally. My GH is rather low too ~.5.
Tank is 17.6 Gallon. Eihem Ecco filter, Aeration.
Black gravel substrate, planted, one driftwood.

My KH is very low, .5 KH, I have an AZOO KH+ liquid
but not surprisingly that moves the Ph way past 7 when
I add it to change my KH in a recommended dose.

My fish panic when this happens, in fact I have taken
to spread the dose over a few hours.
I then add the Acid Buffer (Better than PH down)
to lower the PH.

After this process the KH seems slightly higher (1.5).
Still, it seems like a silly way to keep KH at what
it should be, which is apparently around 3-3.5.

My questions;

a) Should I be doing this?
Adding KH+ then immediately countering the PH
spike with Acid Buffer?

b) Is there another way of increasing KH without
increasing Ph. I think not since KH is also known
as Alkalinity.

c) How do others keep their KH at around 3?

d) I really dont want to put crap in the water
that I dont have to. KH+, Acid Buffer. sounds
silly to me.

HELP!

 

[Faramir]

You're using CO2?

Forget the acid buffer.

Get your KH to about 3-4 using sodium bicarb. Then use the CO2 to return it to around 6.7 (plantbrain is the man to tell you the ideal figure). Adding acid buffer will reverse the increase in KH - that's how it works. You're putting it in only to take it out again.

With your current readings - .5 KH, pH 6.5, you have only about 6ppm CO2. Raise the KH to 4; with the CO2 still at about 6ppm your pH will leap to around 7.3. So increase the CO2 until the pH drops back to around 6.6, and your CO2 will be perfect, and your pH about right for discus. And the plants will be happy.

But I have to say that this tank is far too small for discus.

 

[Wulfy]

Thanks Faramir.

I find that there is very little understanding of the relationship between pH/KH and how to maintain one
without messing with the other.

I read that bicarb will bump the Ph anyway


Yes I am aware that the 17G is too small for for Discus.
However I intend to get small ones, 1inch ones.
By the time they grow slightly larger in 12 months or so
I will be getting an 88 gallon tank.

 

[Faramir]

Yes, bicarb will bump up the pH. But you'll bring it back down with the CO2. That's how it works. If you read my post again you'll see that it will initially rise to 7.3. The CO2 will bring it back down.

 

[wetmanNY]

It makes sense to add CO2 to a planted tank, as a source of carbon for plants in situations where the carbon is locked up as carbonate.

In a Discus tank, a pH in the low 6es is desirable. What you want is a minimum of buffer so the pH doesn't frop below 6.2 or so, under the pressure of bio-acidification. A little crushed coral (aragonite) in the filter will serve. Sodium bicarbonate adds sodium and gives a pH boot, but no longer-term stability.

Discus profit from tannins too, especially if you want to breed them: peat tea, commercial "blackwater" extracts, leaf litter, used green tea bags etc etc.

Water changes will getall that stuff out of the system.