NOOB: Water Buffering

[Enjoy]

Hi Gents,

I'm a little confused regarding a few aspects of buffering within the planted tank.
I have very soft water where. KH = 1.5 GH = 3.5.
For a CO2 injected tank, I have been lead to believe my PH will swing quite drastically.

Due to this info I am investigating adding limestone chips to my filter to add buffering capacity, to at least keep the PH swings gentler and as small as possible.

I understand how the buffer (CO3) binds to the H+ ions, making the water more basic. Therefore effectively mitigating pH crashes and radically fast pHswings? But does this mean the injected CO2 breaks these bonds with carbonic acid or is this just an increase of H+ ions leading to the pH droping again during the CO2 inject hours?

What happens to the leftover Ca and other minerals released? Sure fish and plants may uptake a minimal amount but won't the constant lowering of thepH cause the limestone to continually release these into the water column leading to a KH/GH of insane proportions? Or will an equilibrium be reached (less work - woudn't that be nice!).

 

[Rahms]

I don't think I've seen anyone mess with their water to prevent pH changes because of CO2, and there are definitely others with water this soft growing excellent tanks. I wouldn't worry about it from a tank health point of view, but if you just want to read up, this thread tries to understand it: http://www.ukaps.org/forum/threads/question-for-ceg4048.36402/ As you can see, we butchered the science. The real take-away is that the pH drop you're looking for is approximately the same at all hardness. There's some variation but if you aim for a 1.0 pH drop you'll be fine whether its soft or liquid rock.

 

[EnderUK]

What happens to the leftover Ca and other minerals released? Sure fish and plants may uptake a minimal amount but won't the constant lowering of thepH cause the limestone to continually release these into the water column leading to a KH/GH of insane proportions? Or will an equilibrium be reached (less work - woudn't that be nice!).

It's not going to make a huge difference really as with each 50% change you'll be resetting your TDS. I had soil with lime in it and my TDS would hit the 400s before going back to 200 after a 75% water change (85 tap). Some sort of lime in the tank you're pH will probably be around 7.8 dropping to 6.8 with CO2 on. Now I'm not saying you need to add lime into your tank (possibly if you have snails in the tank), my high tech tank just has sand in it now and it goes from about 6.4 to 5.6 with CO2. So either way it really doesn't matter.

 

[Enjoy]

@Rahms
holy smoke what a thread you posted.
Got quite heated at some point.

@EnderUK
I will be using aquasoil and I really don't know what kind of ph drop to expect.
I'm basically looking to keep my PH above 6 around the 7.8 - 6.8 so yeah I will be adding a small ammount of lime to the tank.
From what you say, it appears the limestone will continue to dissolve solids into the tank, but I imagine at quite a slow rate so yeah.
Nice to know it will be reset with water changes etc etc, since I have water with minimal TDS.

 

[Tim Harrison]

Dude...the science is baffling - but the gist is that it doesn't matter...just maintain good husbandry and all will be fine...